Courses

# RD Sharma Solutions (Part - 1) - Ex-23.2, Data Handling II Central Values, Class 7, Math Class 7 Notes | EduRev

## RD Sharma Solutions for Class 7 Mathematics

Created by: Abhishek Kapoor

## Class 7 : RD Sharma Solutions (Part - 1) - Ex-23.2, Data Handling II Central Values, Class 7, Math Class 7 Notes | EduRev

The document RD Sharma Solutions (Part - 1) - Ex-23.2, Data Handling II Central Values, Class 7, Math Class 7 Notes | EduRev is a part of the Class 7 Course RD Sharma Solutions for Class 7 Mathematics.
All you need of Class 7 at this link: Class 7

#### Question 1:

A die was thrown 20 times and the following scores were recorded:
5, 2, 1, 3, 4, 4, 5, 6, 2, 2, 4, 5, 5, 6, 2, 2, 4, 5, 5, 1
Prepare the frequency table of the scores on the upper face of the die and find the mean score.

The frequency table for the given data is as follows: In order to compute the arithmetic mean, we prepare the following table:

Computation of Arithmetic Mean    #### Question 2:

The daily wages (in Rs) of 15 workers in a factory are given below:
200, 180, 150, 150, 130, 180, 180, 200, 150, 130, 180, 180, 200, 150, 180
Prepare the frequency table and find the mean wage.

The frequency table for the given data is as follows: In order to compute the mean wage, we prepare the following table:

 xi fi fi xi 130 2 260 150 4 600 180 6 1080 200 3 600 Total   #### Question 3:

The following table shows the weights (in kg) of 15 workers in a factory: Calculate the mean weight.

Calculation of Mean

Calculation of Mean

 xi fi fi xi 60 4 240 63 5 315 66 3 198 72 1 72 75 2 150 Total   #### Question 4:

The ages (in years) of 50 students of a class in a school are given below:

 Age (in years): 14 15 16 17 18 Numbers of students: 15 14 10 8 3

Find the mean age

Calculation of Mean

 xi fi fi xi 14 15 210 15 14 210 16 10 160 17 8 136 18 3 54 Total   #### Question 5:

Calculate the mean for the following distribution:

 x : 5 6 7 8 9 f : 4 8 14 11 3

Calculation of Mean

 xi fi fi xi 5 4 20 6 8 48 7 14 98 8 11 88 9 3 27 Total   #### Question 6:

Find the mean of the following data:

 x: 19 21 23 25 27 29 31 f: 13 15 16 18 16 15 13

Calculation of Mean

 xi fi fixi 19 13 247 21 15 315 23 16 368 25 18 450 27 16 432 29 15 435 31 13 403 Total   #### Question 7:

The mean of the following data is 20.6. Find the value of p.

 x: 10 15 p 25 35 f: 3 10 25 7 5

Calculation of Mean

 xi fi fi xi 10 3 30 15 10 150 p 25 25p 25 7 175 35 5 175 Total  We have:  ⇒20.6×50 = 530 +25p  ⇒1030 = 530 +25p
⇒1030 − 530 = 25p  ⇒500 = 25p
⇒p = 500/25 ⇒ p = 20

#### Question 8:

If the mean of the following data is 15, find p.

 x: 5 10 15 20 25 f: 6 p 6 10 5

Calculation of Mean

 xi fi fi xi 5 6 30 10 p 10p 15 6 90 20 10 200 25 5 125 Total  We have:  ⇒15 (27 +p) = 445 +10p ⇒405 + 15p =445 +10p
⇒15p − 10p = 445 −405 ⇒5p = 40 ⇒p = 40÷5

Therefore, p =  8.

#### Question 9:

Find the value of p for the following distribution whose mean is 16.6

 x: 8 12 15 p 20 25 30 f: 12 16 20 24 16 8 4

Calculation of Mean

 xi fi fixi 8 12 96 12 16 192 15 20 300 p 24 24p 20 16 320 25 8 200 30 4 120 Total  We have:  ⇒16.6×100 = 1228 +24p
⇒1660 = 1228 +24p
⇒1660 − 1228 = 24p
⇒432 = 24p
⇒p = 432/24
⇒p =18

#### Question 10:

Find the missing value of p for the following distribution whose mean is 12.58

 x: 5 8 10 12 p 20 25 f: 2 5 8 22 7 4 2

Calculation of Mean

 xi fi fixi 5 2 10 8 5 40 10 8 80 12 22 264 p 7 7p 20 4 80 25 2 50 Total  We have:  ⇒12.58×50 = 524 +7p
⇒629 = 524 +7p
⇒629 − 524 = 7p
⇒105 = 7p
⇒p = 105/ 7
⇒p =15.

#### Question 11:

Find the missing frequency (p) for the following distribution whose mean is 7.68

 x: 3 5 7 9 11 13 f: 6 8 15 p 8 4

Calculation of Mean

 xi fi fi xi 3 6 18 5 8 40 7 15 105 9 p 9p 11 8 88 13 4 52 Total  We have:  ⇒7.68 × (41 +p) =303 +9p
⇒314.88 + 7.68p = 303 +9p
⇒314.88 −303 = 9p −7.68p
⇒11.88 = 1.32p #### Question 12:

Find the value of p, if the mean of the following distribution is 20

 x: 15 17 19 20 + p 23 f: 2 3 4 5 p 6

Calculation of Mean

 xi fi fi xi 15 2 30 17 3 51 19 4 76 20 + p 5p (20+p)5p 23 6 138 Total  We have:  ⇒20 × (15 +5p) =295 + (20+p)5p⇒300+ 100p = 295 +100p + 5p

⇒ 300 - 295 + 100p -100p = 5p2
⇒ 5 = 5p2
⇒ p2 = 1

97 docs

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

;