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Data Handling – II (Central Values Exercise 23.3) RD Sharma Solutions | Mathematics (Maths) Class 7 PDF Download

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 Page 1


 
 
 
 
 
    
 
        
 
Find the median of the following data (1 – 8) 
1. 83, 37, 70, 29, 45, 63, 41, 70, 34, 54 
 
Solution: 
First we have to arrange given data into ascending order, 
29, 34, 37, 41, 45, 54, 63, 70, 70, 83 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (45 + 54)/2 
= 49.5 
Hence median for given data = 49.5 
 
2. 133, 73, 89, 108, 94,104, 94, 85, 100, 120 
 
Solution: 
First we have to arrange given data into ascending order, 
73, 85, 89, 94, 100, 104, 108, 120, 133 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (94 + 100)/2 
= 97 
Hence median for given data = 97 
 
3. 31, 38, 27, 28, 36, 25, 35, 40 
 
Solution: 
First we have to arrange given data into ascending order 
25, 27, 28, 31, 35, 36, 38, 40 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (31 + 35)/2 
Page 2


 
 
 
 
 
    
 
        
 
Find the median of the following data (1 – 8) 
1. 83, 37, 70, 29, 45, 63, 41, 70, 34, 54 
 
Solution: 
First we have to arrange given data into ascending order, 
29, 34, 37, 41, 45, 54, 63, 70, 70, 83 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (45 + 54)/2 
= 49.5 
Hence median for given data = 49.5 
 
2. 133, 73, 89, 108, 94,104, 94, 85, 100, 120 
 
Solution: 
First we have to arrange given data into ascending order, 
73, 85, 89, 94, 100, 104, 108, 120, 133 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (94 + 100)/2 
= 97 
Hence median for given data = 97 
 
3. 31, 38, 27, 28, 36, 25, 35, 40 
 
Solution: 
First we have to arrange given data into ascending order 
25, 27, 28, 31, 35, 36, 38, 40 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (31 + 35)/2 
 
 
 
 
 
    
 
= 33 
Hence median for given data = 33 
 
4. 15, 6, 16, 8, 22, 21, 9, 18, 25 
 
Solution: 
First we have to arrange given data into ascending order 
6, 8, 9, 15, 16, 18, 21, 22, 25 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 16 
 
5. 41, 43,127, 99, 71, 92, 71, 58, 57 
 
Solution: 
First we have to arrange given data into ascending order 
41, 43, 57, 58, 71, 71, 92, 99, 127 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 71 
 
6. 25, 34, 31, 23, 22, 26, 35, 29, 20, 32 
 
Solution: 
First we have to arrange given data into ascending order, 
20, 22, 23, 25, 26, 29, 31, 32, 34, 35 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (26 + 29)/2 
= 27.5 
Hence median for given data = 27.5 
 
7. 12, 17, 3, 14, 5, 8, 7, 15 
 
Page 3


 
 
 
 
 
    
 
        
 
Find the median of the following data (1 – 8) 
1. 83, 37, 70, 29, 45, 63, 41, 70, 34, 54 
 
Solution: 
First we have to arrange given data into ascending order, 
29, 34, 37, 41, 45, 54, 63, 70, 70, 83 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (45 + 54)/2 
= 49.5 
Hence median for given data = 49.5 
 
2. 133, 73, 89, 108, 94,104, 94, 85, 100, 120 
 
Solution: 
First we have to arrange given data into ascending order, 
73, 85, 89, 94, 100, 104, 108, 120, 133 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (94 + 100)/2 
= 97 
Hence median for given data = 97 
 
3. 31, 38, 27, 28, 36, 25, 35, 40 
 
Solution: 
First we have to arrange given data into ascending order 
25, 27, 28, 31, 35, 36, 38, 40 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (31 + 35)/2 
 
 
 
 
 
    
 
= 33 
Hence median for given data = 33 
 
4. 15, 6, 16, 8, 22, 21, 9, 18, 25 
 
Solution: 
First we have to arrange given data into ascending order 
6, 8, 9, 15, 16, 18, 21, 22, 25 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 16 
 
5. 41, 43,127, 99, 71, 92, 71, 58, 57 
 
Solution: 
First we have to arrange given data into ascending order 
41, 43, 57, 58, 71, 71, 92, 99, 127 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 71 
 
6. 25, 34, 31, 23, 22, 26, 35, 29, 20, 32 
 
Solution: 
First we have to arrange given data into ascending order, 
20, 22, 23, 25, 26, 29, 31, 32, 34, 35 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (26 + 29)/2 
= 27.5 
Hence median for given data = 27.5 
 
7. 12, 17, 3, 14, 5, 8, 7, 15 
 
 
 
 
 
 
    
 
Solution: 
First we have to arrange given data into ascending order, 
3, 5, 7, 8, 12, 14, 15, 17 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n +1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (8 + 12)/2 
= 10 
Hence median for given data = 10 
 
8. 92, 35, 67, 85, 72, 81, 56, 51, 42, 69 
 
Solution: 
First we have to arrange given data into ascending order, 
35, 42, 51, 56, 67, 69, 72, 81, 85, 92 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (67 + 69)/2 
= 68 
Hence median for given data = 68 
 
9. Numbers 50, 42, 35, 2x +10, 2x – 8, 12, 11, 8, 6 are written in descending order and 
their median is 25, find x. 
 
Solution: 
Here, the number of observations n is 9.  
Since n is odd, the median is the n+12th observation, i.e., the 5
th
 observation. 
As the numbers are arranged in the descending order, we therefore observe from the 
last. 
Median = 5
th
 observation. 
=> 25 = 2x – 8 
=> 2x = 25 + 8 
=> 2x = 33 
=> x = (33/2) 
x = 16.5 
 
Page 4


 
 
 
 
 
    
 
        
 
Find the median of the following data (1 – 8) 
1. 83, 37, 70, 29, 45, 63, 41, 70, 34, 54 
 
Solution: 
First we have to arrange given data into ascending order, 
29, 34, 37, 41, 45, 54, 63, 70, 70, 83 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (45 + 54)/2 
= 49.5 
Hence median for given data = 49.5 
 
2. 133, 73, 89, 108, 94,104, 94, 85, 100, 120 
 
Solution: 
First we have to arrange given data into ascending order, 
73, 85, 89, 94, 100, 104, 108, 120, 133 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (94 + 100)/2 
= 97 
Hence median for given data = 97 
 
3. 31, 38, 27, 28, 36, 25, 35, 40 
 
Solution: 
First we have to arrange given data into ascending order 
25, 27, 28, 31, 35, 36, 38, 40 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (31 + 35)/2 
 
 
 
 
 
    
 
= 33 
Hence median for given data = 33 
 
4. 15, 6, 16, 8, 22, 21, 9, 18, 25 
 
Solution: 
First we have to arrange given data into ascending order 
6, 8, 9, 15, 16, 18, 21, 22, 25 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 16 
 
5. 41, 43,127, 99, 71, 92, 71, 58, 57 
 
Solution: 
First we have to arrange given data into ascending order 
41, 43, 57, 58, 71, 71, 92, 99, 127 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 71 
 
6. 25, 34, 31, 23, 22, 26, 35, 29, 20, 32 
 
Solution: 
First we have to arrange given data into ascending order, 
20, 22, 23, 25, 26, 29, 31, 32, 34, 35 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (26 + 29)/2 
= 27.5 
Hence median for given data = 27.5 
 
7. 12, 17, 3, 14, 5, 8, 7, 15 
 
 
 
 
 
 
    
 
Solution: 
First we have to arrange given data into ascending order, 
3, 5, 7, 8, 12, 14, 15, 17 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n +1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (8 + 12)/2 
= 10 
Hence median for given data = 10 
 
8. 92, 35, 67, 85, 72, 81, 56, 51, 42, 69 
 
Solution: 
First we have to arrange given data into ascending order, 
35, 42, 51, 56, 67, 69, 72, 81, 85, 92 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (67 + 69)/2 
= 68 
Hence median for given data = 68 
 
9. Numbers 50, 42, 35, 2x +10, 2x – 8, 12, 11, 8, 6 are written in descending order and 
their median is 25, find x. 
 
Solution: 
Here, the number of observations n is 9.  
Since n is odd, the median is the n+12th observation, i.e., the 5
th
 observation. 
As the numbers are arranged in the descending order, we therefore observe from the 
last. 
Median = 5
th
 observation. 
=> 25 = 2x – 8 
=> 2x = 25 + 8 
=> 2x = 33 
=> x = (33/2) 
x = 16.5 
 
 
 
 
 
 
    
 
10. Find the median of the following observations: 46, 64, 87, 41, 58, 77, 35, 90, 55, 92, 
33. If 92 is replaced by 99 and 41 by 43 in the above data, find the new median? 
 
Solution: 
Arranging the given data in ascending order, we have: 
33, 35, 41, 46, 55, 58, 64, 77, 87, 90, 92 
Here, the number of observations n is 11 (odd). 
Since the number of observations is odd, therefore, 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 58. 
Hence, median = 58. 
If 92 is replaced by 99 and 41 by 43, then the new observations arranged in ascending 
order are: 
33, 35, 43, 46, 55, 58, 64, 77, 87, 90, 99 
New median = Value of the 6
th
 observation = 58. 
 
11. Find the median of the following data: 41, 43, 127, 99, 61, 92, 71, 58, 57, If 58 is 
replaced by 85, what will be the new median? 
 
Solution: 
Arranging the given data in ascending order, we have: 
41, 43, 57, 58, 61, 71, 92, 99,127 
Here, the number of observations, n, is 9(odd). 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
Hence, the median = 61. 
If 58 is replaced by 85, then the new observations arranged in ascending order are: 
41, 43, 57, 61, 71, 85, 92, 99, 12 
New median = Value of the 5
th
 observation = 71. 
 
12. The weights (in kg) of 15 students are: 31, 35, 27, 29, 32, 43, 37, 41, 34, 28, 36, 44, 
45, 42, 30. Find the median. If the weight 44 kg is replaced by 46 kg and 27 kg by 25 kg, 
find the new median. 
 
Solution: 
Arranging the given data in ascending order, we have: 
Page 5


 
 
 
 
 
    
 
        
 
Find the median of the following data (1 – 8) 
1. 83, 37, 70, 29, 45, 63, 41, 70, 34, 54 
 
Solution: 
First we have to arrange given data into ascending order, 
29, 34, 37, 41, 45, 54, 63, 70, 70, 83 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (45 + 54)/2 
= 49.5 
Hence median for given data = 49.5 
 
2. 133, 73, 89, 108, 94,104, 94, 85, 100, 120 
 
Solution: 
First we have to arrange given data into ascending order, 
73, 85, 89, 94, 100, 104, 108, 120, 133 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (94 + 100)/2 
= 97 
Hence median for given data = 97 
 
3. 31, 38, 27, 28, 36, 25, 35, 40 
 
Solution: 
First we have to arrange given data into ascending order 
25, 27, 28, 31, 35, 36, 38, 40 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (31 + 35)/2 
 
 
 
 
 
    
 
= 33 
Hence median for given data = 33 
 
4. 15, 6, 16, 8, 22, 21, 9, 18, 25 
 
Solution: 
First we have to arrange given data into ascending order 
6, 8, 9, 15, 16, 18, 21, 22, 25 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 16 
 
5. 41, 43,127, 99, 71, 92, 71, 58, 57 
 
Solution: 
First we have to arrange given data into ascending order 
41, 43, 57, 58, 71, 71, 92, 99, 127 
Given number of observations, n = 9 (odd) 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 71 
 
6. 25, 34, 31, 23, 22, 26, 35, 29, 20, 32 
 
Solution: 
First we have to arrange given data into ascending order, 
20, 22, 23, 25, 26, 29, 31, 32, 34, 35 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (26 + 29)/2 
= 27.5 
Hence median for given data = 27.5 
 
7. 12, 17, 3, 14, 5, 8, 7, 15 
 
 
 
 
 
 
    
 
Solution: 
First we have to arrange given data into ascending order, 
3, 5, 7, 8, 12, 14, 15, 17 
Given number of observations, n = 8 (even) 
Therefore median = (n/2)
th
 term + ((n +1)/2)
th
 term 
Median = (value of 4
th
 term + value of 5
th
 term)/2 
= (8 + 12)/2 
= 10 
Hence median for given data = 10 
 
8. 92, 35, 67, 85, 72, 81, 56, 51, 42, 69 
 
Solution: 
First we have to arrange given data into ascending order, 
35, 42, 51, 56, 67, 69, 72, 81, 85, 92 
Given number of observations, n = 10 (even) 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
= (67 + 69)/2 
= 68 
Hence median for given data = 68 
 
9. Numbers 50, 42, 35, 2x +10, 2x – 8, 12, 11, 8, 6 are written in descending order and 
their median is 25, find x. 
 
Solution: 
Here, the number of observations n is 9.  
Since n is odd, the median is the n+12th observation, i.e., the 5
th
 observation. 
As the numbers are arranged in the descending order, we therefore observe from the 
last. 
Median = 5
th
 observation. 
=> 25 = 2x – 8 
=> 2x = 25 + 8 
=> 2x = 33 
=> x = (33/2) 
x = 16.5 
 
 
 
 
 
 
    
 
10. Find the median of the following observations: 46, 64, 87, 41, 58, 77, 35, 90, 55, 92, 
33. If 92 is replaced by 99 and 41 by 43 in the above data, find the new median? 
 
Solution: 
Arranging the given data in ascending order, we have: 
33, 35, 41, 46, 55, 58, 64, 77, 87, 90, 92 
Here, the number of observations n is 11 (odd). 
Since the number of observations is odd, therefore, 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
= 58. 
Hence, median = 58. 
If 92 is replaced by 99 and 41 by 43, then the new observations arranged in ascending 
order are: 
33, 35, 43, 46, 55, 58, 64, 77, 87, 90, 99 
New median = Value of the 6
th
 observation = 58. 
 
11. Find the median of the following data: 41, 43, 127, 99, 61, 92, 71, 58, 57, If 58 is 
replaced by 85, what will be the new median? 
 
Solution: 
Arranging the given data in ascending order, we have: 
41, 43, 57, 58, 61, 71, 92, 99,127 
Here, the number of observations, n, is 9(odd). 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 5
th
 term 
Hence, the median = 61. 
If 58 is replaced by 85, then the new observations arranged in ascending order are: 
41, 43, 57, 61, 71, 85, 92, 99, 12 
New median = Value of the 5
th
 observation = 71. 
 
12. The weights (in kg) of 15 students are: 31, 35, 27, 29, 32, 43, 37, 41, 34, 28, 36, 44, 
45, 42, 30. Find the median. If the weight 44 kg is replaced by 46 kg and 27 kg by 25 kg, 
find the new median. 
 
Solution: 
Arranging the given data in ascending order, we have: 
 
 
 
 
 
    
 
27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 41, 42, 43, 44, 45 
Here, the number of observations n is 15(odd). 
Since the number of observations is odd, therefore, 
Therefore median = ((n+1)/2)
th
 term 
Median = value of 8
th
 term 
Hence, median = 35 kg. 
If 44 kg is replaced by 46 kg and 27 kg by 25 kg, then the new observations arranged in 
ascending order are: 
25, 28, 29, 30, 31, 32, 34, 35, 36, 37, 41, 42, 43, 45, 46 
? New median = Value of the 8
th
 observation = 35 kg. 
 
13. The following observations have been arranged in ascending order. If the median 
of the data is 63, find the value of x: 29, 32, 48, 50, x, x + 2, 72, 78, 84, 95 
 
Solution: 
Here, the number of observations n is 10. Since n is even, 
Therefore median = (n/2)
th
 term + ((n + 1)/2)
th
 term 
Median = (value of 5
th
 term + value of 6
th
 term)/2 
63 = x + (x + 2)/2 
63 = (2x + 2)/2 
63 = 2 (x + 1)/2 
63 = x + 1 
x = 63 – 1 
x = 62 
 
 
 
 
 
 
 
 
 
 
 
 
 
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