Average Questions Answers
1. Average of all prime numbers between 30 to 50
37
37.8
39
39.8
Answer: Option D
Explanation:
Prime numbers between 30 and 50 are:
31, 37, 41, 43, 47
Average of prime numbers between 30 to 50 will be
(31+37+41+43+475)=1995=39.8
2. Reeya obtained 65, 67, 76, 82 and 85 out of 100 in different subjects, What will be the average.
70
75
80
85
Answer: Option B
Explanation:
(65+67+76+82+855)=75
3. Find the sum of first 30 natural numbers
470
468
465
463
Answer: Option C
Explanation:
Sum of n natural numbers
=n(n+1)2
=30(30+1)2=30(31)2=465
4. Find the average of first 10 multiples of 7
35.5
37.5
38.5
40.5
Answer: Option C
Explanation:
=7(1+2+3+...+10)10
=7(10(10+1))10×2
=7(110)10×2=38.5
5. The average of four consecutive odd numbers is 24. Find the largest number.
25
27
29
31
Answer: Option B
Explanation:
Let the numbers are x, x+2, x+4, x+6, then
=>x+(x+2)+(x+4)+(x+6)4=24
=>4x+12)4=24
=>x+3=24=>x=21
So largest number is 21 + 6 = 27
6. Average of 10 numbers is zero. At most how many numbers may be greater than zero
0
1
5
9
Answer: Option D
Explanation:
7. Find the average of all numbers between 6 and 34 which are divisible by 5
15
20
25
30
Answer: Option B
Explanation:
Average=(10+15+20+25+305)=1005=20
8. Average of first five multiples of 3 is
9
11
13
15
Answer: Option A
Explanation:
Average=3(1+2+3+4+5)5=455=9
9. Average age of boys in a class is 16 years and average age of girls is 15 years, what is the average age
of all
15.5
15
16
Cant be computed
Answer: Option D
Explanation:
As number of girls and boys is not given so result cant be computed
10. A library has an average of 510 visitors on Sundays and 240 on other day. The average number of
visitors in a month of 30 days starting with sunday is
280
285
290
295
Answer: Option B
Explanation:
As the month begin with sunday, so there will be five sundays in the month. So result will be:
=(510×5+240×2530)=(855030)=285
11. A batsman makes a score of 87 runs in the 17th match and thus increases his average by 3. Find his
average after 17th match
36
37
38
39
Answer: Option D
Explanation:
Let the average after 17th match is x
then the average before 17th match is x-3
so 16(x-3) + 87 = 17x
=> x = 87 - 48 = 39
12. Average weight of 10 people increased by 1.5 kg when one person of 45 kg is replaced by a new
man. Then weight of the new man is
50
55
60
65
Answer: Option C
Explanation:
Total weight increased is 1.5 * 10 = 15.
So weight of new person is 45+15 = 60
13. Average of five numbers is 27. If one number is excluded the average becomes 25. The excluded
number is
35
45
55
65
Answer: Option A
Explanation:
Number is (5*27) - (4*25) = 135-100 = 35
14. The average score of a cricketer for ten matches is 38.9 runs. If the average for first six matches is
42, then average for last four matches is
33.25
32.25
34.25
34.50
Answer: Option C
Explanation:
=(38.9×10)−(42×6)4
=(1216−750)4=34.25
15. Average of 10 matches is 32, How many runs one should should score to increase his average by 4
runs.
70
76
78
80
Answer: Option B
Explanation:
Average after 11 innings should be 36
So, Required score = (11 * 36) - (10 * 32)
= 396 - 320 = 76
16. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the
average marks of all the students is
54.48
54.68
54.60
54.58
Answer: Option B
Explanation:
(55×50)+(60×55)+(45×60)55+60+45
8750160=54.68
17. The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the
child 5 years ago was 20 years. The present age of the husband is
40
35
45
55
Answer: Option A
Explanation:
Sum of the present ages of husband, wife and child = (27 * 3 + 3 * 3) years = 90 years.
Sum of the present ages of wife and child = (20 * 2 + 5 * 2) years = 50 years.
Husband's present age = (90 - 50) years = 40 years
18. The average of six numbers is X and the average of three of these is Y.If the average of the remaining
three is z, then
x=y+z
2x = y + z
x = 2y + z
x = y + 2z
Answer: Option B
Explanation:
X =((3y+3z)/6)
or
2X= y + z
19. A motorist travel to a place 150 km away at an avearge speed of 50 km/hr and returns ar 30
km/hr.His average speed for the whole jouney in km/hr is
36.5 km/hr
37.5 km/hr
35.5 km/hr
34.5 km/hr
Answer: Option B
Explanation:
Average speed will be
2xyx+ykm/hr
= \frac{2(50)(30)}{50+30} km/hr
= 37.5 km/hr
20. The average age of the mother and her six children is 12 years which is reduced by 5 years if the age
of the mother is excluded. How old is the mother
40
41
42
43
Answer: Option C