While calculating the weight of a group of men, the weight of 63 kg of one of the member was mistakenly written as 83 kg. Due to this the average of the weights increased by half kg. What is the number of men in the group?
C) 40
Explanation: Increase in marks lead to increase in average by ½ So (8363) = x/2 x = 40
A cricketer had an average number of runs as 32 after playing 10innings. If he wants to make his average run rate increased by 4, then how much runs will he have to take in his next inning?
D) 76
Explanation: Average after 10 innings = 32, so after 11 inning = 32+4 = 36 So required runs = (36*11) – (32*10)
The average temperature in Delhi for the first four days of the month was reported as 58^{0} . It reported as 60^{0} for 2nd, 3rd, 4th and 5th days. The ratio of the temperatures of 1st and 5th day was 7 : 8. Find the temperature on the first day.
E) 56^{0}
Explanation: A+B+C+D = 58*4
B+C+D+E = 60*4
Subtract both, E – A = 8 So 8x – 7x = 8, x = 8 So temperature of A(1st day) = 7x = 7*8
For three successive years, the cost of petrol were Rs 20 per litre, Rs 22 per litre and Rs 23.50 per litre respectively. If a man spent an average of Rs 8000 per year on petrol, then he spent what average cost of petrol per litre for the three years?
D) Rs 21.7 Explanation: Quantity used in 1st yr = 8000/20 = 400 l, in 2nd yr = 8000/22 = 363.6, in 3rd yr = 340.4 l Total used in 3 yrs = 1104 litres, total money spent in 3 yrs = 3*8000 = 24000 So average rate of 3 yrs = 24000/1104
In a group of 8 boys, 2 men aged at 21 and 23 were replaced two new boys.Due to this the average cost of the group increased by 2 years. What is the average age of the 2 new boys?
B) 30
Explanation: Average of 8 boys increased by 2, this means the total age of boys increased by 8*2 = 16 yrs So sum of ages of two new boys = 21+23+16 = 60 Average of these = 60/2
The average age of the group having 3 members is 84. One more person joins the group and now the average becomes 80. Now a fifth person comes whose age is 3 years more than that of fourth person replaces the first person. After this the average age of the group becomes 79. What is the age of the first person?
Let the ages of these are A, B, C, D, E
So A+B+C = 84*3 = 252
And A+B+C+D = 80*4 = 320
So D = 320252 = 68,
so E = 68+3 = 71
Now B+C+D+E = 79*4 = 316
(A+B+C+D) – (B+C+D+E) = 320 316
So AE = 4, so
A = 71+4 = 75
3 years ago, the average age of A, B, and C was 27 years. Also 5 years ago, the average age of B and C was 20 years. What is the present age of A?
B) 40
Explanation: Sum of ages of A+B+C 3 yrs ago = 27*3 = 81 So after 3 yrs, i.e. at present their total = 81 + 3*3 = 90 Similarly sum of present age of B&C = 20*2 +5*2 = 50 So present age of A = 9050
Average age of girls in a class is 16 years. If the average of the boys in class is also added, the average becomes 15.5 years. If there were 20 boys in the class with average age 15 years, how many girls were there in the class?
C) 20
Explanation: Let x girls in the class, so 16x + 20*15 = 15.5 (x+20)
In a class, the average marks got by number of students in English is 52.25. 25% students placed in C category made the average of 31 marks, while 20% who were placed in A category made the average of 80 marks. Find the average marks of the remaining students?
D) 51.8
Explanation: Let there are 100 students in the class, then in category A = 20 students, in C = 25 students, remaining = 55 students. Let x be the average of these 55 students.
So 20*80+ 25*31 + 55*x = 52.25*100
The average of 5 numbers is 40. Average of first two and last two is 25 and 45 respectively. Find the middle number.
A) 60
Explanation: 5*40 – (2*25 + 2*45)
If a man spends 1000rs for the first five months, 2000rs for the next four months and 3000rs for the next 3 months and he saves 2000rs in the whole year then his average monthly salary will be ?
Answer – b) 2000 Explanation : 1000*5 + 2000*4 + 3000*3 + 2000 = 24000
24000/12 = 2000
In a family of 6 members, the average age of the family at present is 25 while the age of the youngest member in the family is 5yrs, so what will be the average age of the family at the time of his birth ?
Answer – d) 24 Explanation : sum of ages = 25*6 = 150 At the time of birth, i.e 5 years back, so (1506*5)/5 = 24
The average temperature for the the first 5 month of the year is 40’c and the average temperature from second to sixth month is 42’c and the ratio b/w the temperature of 1 day and the 6 day is 3:4, find the temperature of the sixth day ?
1,2,3,4,5 = 200
2,3,4,5,6 = 210
4x – 3x = 10, so temp on sixth day = 40
The average age of A and B 10 years ago was 20. The average age of A, B and C today is 30, so what will be the age of C after 5 years.
Answer – b) 35 Explanation : A+B = 60.
A,B,C = 90
so Age of C = 30+5 = 35
The average age of 5 children of a family is 10 years but if we include the age of father and mother then the average age becomes 22 years. It is given that father age is 6 years more than the mother so what will be the age of mother at present.
Answer – c) 49 Explanation : sum of age of children = 50 50 + M+ F = 22*7 = 154.
M+F = 104 and F= M+6 . So, M = 49
The batting average of a batsman for 20 innings is 35 and the difference b/w the runs of best inning and worst inning is 50. If these two innings are not included the average becomes 32 for 18 innings. The best score of the batsman is.
Answer – c) 87 Explanation : 35*20 = 700.
Best(B) – Worst(W) = 50 700 – B – H = 18*32= 576. B+H = 124 and BH = 50. So B =87
The average age of a class of 20 students is 12 years. Out of which one student whose age is 10 year left the class and two new boys entered the class. The average of the class remains the same and the difference between the ages of new boys is 4 year. What will be the age of younger one .
Answer – b) 9 Explanation : 240 – 10 + a+ b = 21 * 12 a+ b =22, ab = 4. So, b= 9
The average marks secured by 15 students are 70 and later it was found that one entry is wrong and 65 is written instead of 45. Find out he corrected average.
Answer –b) 68.66 Explanation : (15*7065+45)/15
The average salary of all the workers in factory is 7000. The average salary of 9 mechanic is 5000 and for the rest of the workers it 4000. Find the total number of workers in the factory.
Answer – c) 12 Explanation : Total workers T, so 7000*T = 9*5000 + (T9)*4000.
T = 3 so 3+9 =12
The average age of a couple at the time of marriage was 20 years. After 8 years of marriage they have a baby of 4 years old. Calculate the average age of the family when the baby was born.
Answer – a) 16 Explanation : At the time of marriage H+W = 40. So when baby was means means after 4 years from their marriage so (40+4+4)/3 = 16
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