SHIROMANI INSTITUTE

AVERAGE
6. Find the average of all the prime
numbers between 60 and 80.
Sum of all the given observation (a) 68.4 (b) 70.2 (c) 72.8 (d) 74.6
= Average × Number of these 7. Find the mean of the first ten even
observations numbers.
The average of first n even numbers (a) 10 (b) 11 (c) 9 (d) 5.5
= (n + 1)
8. Find the average of first 9 prime
The average of first n odd numbers
number.
=n
(a) 9.8 (b) 10.3
The average of first n natural numbers
n  1
(c) 12.7 (d) 11.1
=  
 2  9. If average of the following marks
1. Find the average of first 20 natural obtained by students of Class-V is 35.
numbers 26, 45, 37, 43, 49, 20, x, 22 and 30.
(a) 11 (b) 12.5 (c) 10.5 (d) 11.5 Find unknown mark i.e.x.
2. What is the average of the following (a) 33 (b) 49 (c) 37 (d) 43
numbers? 10. The ages of 5 children are 13, 15, 11, 9
12, 5, 10, 3 and 8 and 8 years respectively. Find their
(a) 7.6 (b) 76 (c) 10.5 (d) 9.5 average age.
3. What is the average of 4.2, 2.7, 5.6 (a) 10.6 years (b) 11.2 years
and 8.6 ? (c) 10.2 years (d) 11.8 years
(a) 5.25 (b) 5.275
11. The average age of 5 boys is 13 years.
(c) 5.225 (d) 6.275
One more boy joins them and the
4. The height of four students are 150
average age becomes 12 years. Find
cm, 160 cm, 158 cm and 162 cm.
the age of the boy who joins last.
(a) 158 cm (b) 156.5 cm
(a) 5 years (b) 6 years
(c) 157 cm (d) 157.5 cm
(c) 7 years (d) 8 years
5. The average weights of three students
are 42.5 kg, 54 kg, and 58 kg. Find the 12. The marks obtained by a student in
average weight of the students. five examinations are 90, 92, 93, 95
(a) 51.5 kg (b) 52.5 kg and 90. Find his average marks.
(c) 51 kg (d) 50 kg (a) 91 (b) 92 (c) 93 (d) 94

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13. The average age of a class of 40 19. The population of four towns is 35560,
students is 18 years. When a teacher 30000, 27500 and 25600 respectively.
joins them their average age becomes What is the average population of the
19 years. Find the teacher’s age. town?
(a) 57 years (b) 61 years (a) 29665 (b) 28865
(c) 53 years (d) 59 years (c) 29225 (d) 28485
14. If the average of 14, 17, 21, 24, 26 and 20. The average age of 3 sisters is 15
x is 20, then find the value of x. years. If the ages of two sisters are 12
(a) 16 (b) 17 years and 15 years, then the age of
(c) 18 (d) 19 the third sister is
15. Find the average of 12 numbers if the (a) 21 years (b) 17 years
average of the first 8 numbers is 21 (c) 18 years (d) 16 years
and the average of the last four 21. What is the average of the first 15
number is 18. counting numbers?
(a) 19 (b) 19.5 (a) 8 (b) 15 (c) 16 (d) 7.5
(c) 20 (d) 20.5 22. The average weight of 20 boys in a
16. A car travels 58 km in the first hour, 62 class is 160 kg and that of the
km in the second hour and 75 km in remaining 5 boys is 50 kg. Find the
the third hour. Find the average speed average weight of all the boys in the
of the car. class.
(a) 65 km/hr (b) 63 km/hr (a) 138 kg (b) 183 kg
(c) 64 km/hr (d) 67 km/hr (c) 140 kg (d) 150 kg
17. The average age of 25 students of a 23. The average marks obtained by 7
class is 13 years. Out of them, the students in a group is 226. If the marks
average age of 15 students is 18 years. obtained by six of them are 340, 180,
Find the average age of the remaining 260, 56, 275 and 307 respectively, find
students. the marks obtained by the seventh
(a) 4.5 years (b) 5.2 years student.
(c) 5.5 years (d) 5.7 years (a) 160 (b) 162 (c) 163 (d) 164
18. The depth of a swimming pool at six 24. The average weight of 6 boys gets
different places is 344 cm, 275 cm, 192 increased by 5 kg if a boy having
cm, 147 cm, 233 cm and 300 cm. Find weight 20 kg is replaced by a new boy.
the average depth of the swimming What is the weight of the new boy?
pool. (a) 41 kg (b) 50 kg (c) 65 kg (d) 49 kg
(a) 236.5 cm (b) 242 cm 25. Average of 1, 3, 5, 7, 9, 11, 13 is
(c) 248.5 cm (d) 252 cm (a) 7 (b) 8 (c) 7.5 (d) 8.5

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26. A library has an average of 510 visitors 33. What is the average of all the odd
on Sundays and 240 on other days. numbers from 25 to 40 ?
The average number of visitors in a (a) 31 (b) 31.5 (c) 32 (d) 32.5
month of 30 days starting with Sunday 34. Find the average of all the multiples of
is twelve lying between 50 to 150.
(a) 280 (b) 285 (c) 290 (d) 295 (a) 102 (b) 101
27. A batsman makes a score of 87 runs in (c) 100 (d) 104
the 17th match and thus increases his
1 3
average by 3. Find his average after 35. The average of 5 and 2 is.
5 10
the 17th match. 15 5 15 15
(a) 4 (b) 3 (c) 3 (d) 2
(a) 36 (b) 37 (c) 38 (d) 39 20 10 20 20

28. The average weight of 16 boys in a 36. The average of 16 numbers is 75.
class is 50.25 kg and that of the Find the sum ?
remaining 8 boys is 45.15 kg. Find the (a) 1100 (b) 1200
average weight of all the boys in the (c) 1210 (d) 1285
class. 37. The average of P numbers is q and the
(a) 47.55 kg (b) 48 kg
average of q numbers is P. Find the
(c) 48.55 kg (d) 49.25 kg
average of all these numbers.
29. Average of 20 results is 18. If 3 is 2pq pq
(a) (b)
subtracted from each result, then pq pq
what will be the new average? pq pq  qp
(c) (d)
(a) 21 (b) 15 (c) 16 (d) 17 pq pq

30. What is the average of first seven 38. The average of 5 numbers is 30. If one
composite numbers ? number is excluded from them, then
(a) 8 (b) 8.5 (c) 7.5 (d) 9 the average is decreased by 2. Find the
31. What is the average of first six excluded number.
multiples of 15 ? (a) 30 (b) 35 (c) 32 (d) 38
(a) 52 (b) 52.5 (c) 51 (d) 51.5 39. The average of 11 numbers is 25. If 5 is
32. What is the average of all the even added to each number, then the new
numbers from 50 to 60 ? average will be.
(a) 50 (b) 55 (c) 60 (d) 60.5 (a) 28 (b) 30 (c) 32 (d) 30.5

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 ANSWER-KEY
1. (C) 2. (A) 3. (B) 4. (D) 5. (A) 6. (B) 7. (B) 8. (D)
9. (D) 10. (B) 11. (C) 12. (B) 13. (D) 14. (C) 15. (C) 16. (A)
17. (C) 18. (C) 19. (A) 20. (C) 21. (A) 22. (A) 23. (D) 24. (B)
25. (A) 26. (B) 27. (D) 28. (C) 29. (B) 30. (D) 31. (B) 32. (B)
33. (C) 34. (A) 35. (C) 36. (B) 37. (D) 38. (D) 39. (B)

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