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- Question
- The average age of three boys is 15 yr. If the ratio of their ages is 3 : 5 : 7, What is the age of the oldest boy?
Options- A. 7 yr
- B. 14 yr
- C. 20 yr
- D. 21 yr
- Correct Answer
- 21 yr
ExplanationTotal age of all three boys
= 3 x 15 = 45 yr
Ratio of ages = 3 : 5 : 7
? Age of the oldest boy
= [7/(3 + 5 + 7)] x 45 = (7/15) x 45 = 21 yr - 1. Three year ago, the average age of a family of five members was 27 yr. The present average age is also 27 yr after the inclusion of a child into the family. Find the age of the child.
Options- A. 16 yr
- B. 12 yr
- C. 24 yr
- D. 20 yr. Discuss
- 2. A cricketer scored some runs in his continuous 9 innings. He scored 100 runs in his 10th innings and increase his average by 8 runs. What was the average of his runs at the end of 10 th innings?
Options- A. 20
- B. 24
- C. 28
- D. 32 Discuss
- 3. The average of four positive integers is 73.5. The highest integer is 108 and the lowest integer is 29, the difference between the remaining two integers is 15. Which of the following is the smaller of the remaining two integers?
Options- A. 80
- B. 86
- C. 73
- D. Cannot be determind Discuss
- 4. A car travels a certain distance from town A to town B at the speed of 42 km/h and from town B to town A at a speed of 48 km/h. What is the average speed of the car?
Options- A. 45 km/h
- B. 46 km/h
- C. 44 km/h
- D. Cannot be determind Discuss
- 5. The average marks of 120 students are 35. if the average of passed stuydents was 39. and failed students was 15 then find the number of students who have passed
Options- A. 80
- B. 100
- C. 120
- D. 140 Discuss
- 6. Nine friends have dinner in a hostel. Eight of them spent ? 12 each on their meals and the ninth spent ? 16 more than the average expenditure of all the nine. Find out the total money spent by them?
Options- A. ? 126
- B. ? 135
- C. ? 111
- D. ? 141 Discuss
- 7. In a certain examination, the average marks of an examinee is 64 per paper. if he had obtained 18 more marks for his Mathematics paper and 4 more marks for his English paper, his average per paper would have been 66. How many papers were there in the examination?
Options- A. 11
- B. 13
- C. 9
- D. 15 Discuss
- 8. The average markes obtained by 120 students in an examination is 30. if the aveage marks of passed students is 40 and that of the failed students is 10. what is the 25% of the number of students who passed the examination?
Options- A. 30
- B. 20
- C. 40
- D. 15 Discuss
- 9. A class is divided into two sections A and B. Passing average of 20 students of section A is 80% and passing average of 30 students of sections B is 70%. What is the passing average of both the sections?
Options- A. 72%
- B. 74%
- C. 75%
- D. 77% Discuss
- 10. The average age of 4 member of family is 20 yr. If youngest member is 4 yr. old, What was the average age of family at the time of the birth of youngest member?
Options- A. 27 yr
- B. 231/3 yr
- C. 211/3 yr
- D. 22 yr Discuss
Average problems
Search Results
Correct Answer: 12 yr
Explanation:
Total age of 5 memeber (3 yr ago) = 27 x 5 = 135 yr
Total age of 5 members (at present) = 135 + 5 x 3 = 150 yr.
Let the persent age of child = x
? 27 = (150 + x)/6
? x = 162 - 150 = 12 yr.
Correct Answer: 28
Explanation:
Let average of a inning = x
Total runs = 9x
According to the question,
(9x + 100) /10 = x + 8
? 9x + 100 = 10x + 80
x = 20
Average after 10 inning = 20 + 8 = 28
Correct Answer:
Explanation:
Let one integer be x.
? Other ingeger x + 15
According to the question,
29 + x + x + 15+ 108 = 4 x 73.5
? 2x + 152 = 294
? 2x = 294 - 152 = 142
? x = 142/2 = 71
Correct Answer:
Explanation:
If two equal distance are covered at different speeds at A km/h and B km/h respectively, then
Average speed during the whole journey = 2AB/(A + B) km/h
? Average speed of the car = (2 x 42 x 48) / (42 + 48)
= (2 x 42 x 48)/90
= 44.8 km/h
Correct Answer: 100
Explanation:
Here n = 120, a = 35, x = 39, y = 15
Number of students passed = n (a - y)/(x - y)
= 120(35 - 15)/(39 -15)
= 100 students passed
Correct Answer: ? 126
Explanation:
Let average expenditure of 9 persons = x.
According to the question,
12 x 8 + (x + 16) = 9x
? 8x = 112
? x = 112/8 = 14
? Total money spent = 9x = 9 x 14 = ? 126
Correct Answer: 11
Explanation:
Let the number of papers = x.
According to the question,
64x + 18 + 4 = 66x
? 2x = 22
? x = 22/2 = 11
Correct Answer: 20
Explanation:
Let number of passed students = N
Total marks = 120 x 30
According to the question,
40N + (120 - N) x 10 = 120 x 30
? 3600 = 40N + 1200 - 10N
? 30N = 2400
? N = 2400/30 = 80
? 25% of 80 = 80/4 = 20
Correct Answer: 74%
Explanation:
Here n1 = 20, n2 = 30, a1 = 80%, a2 = 70%
? Total average = (n1a1 + n2a2) / (n1 + n2)
= (20 x 80 + 30 x 70) / (20 + 30)
= (1600 + 2100) / 50
= 74%
Correct Answer: 211/3 yr
Explanation:
Total age of all members of the family (at present) = 20 x 4 = 80
4yr ago, total age of all members = 80 - ( 4 x 4) = 80- 16 = 64 yr.
As 4 yr ago, there were only 3 members in the family
? Average age of the family at the time of the birth of the youngest member
= 64/3
= 211/3 yr
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