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- Question
- 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
- Correct Answer
- 20
ExplanationLet 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 - 1. 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
- 2. 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
- 3. 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 Discuss
- 4. 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
- 5. 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
- 6. 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
- 7. 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
- 8. 3 yr ago, the average age of a family of 5 members was 17 yr. Even after the birth of a child, the aveage is same today. Find out the age of child.
Options- A. 1 yr
- B. 3 yr
- C. 21/2
- D. 2 yr Discuss
- 9. A person bought some oranges worth ? 36 from each of the five markets at ? 1, ? 1.50, ? 1.80, ? 2 and ? 2.25 per orange, respectively. What is the average price of an orange?
Options- A. ? 1.91
- B. ? 2.00
- C. ? 1.58
- D. ? 1.80 Discuss
- 10. Average of a, b and c is 11; average of c, d and e is 17; average of e and f is 22 and average of e and c is 17. Find out the average of a, b, c, d, e and f?
Options- A. 152/3
- B. 181/2
- C. 211/3
- D. 161/2 Discuss
Average problems
Search Results
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: ? 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: 21 yr
Explanation:
Total 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
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: 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
Correct Answer: 2 yr
Explanation:
3 yr ago, total age of 5 members of the family = 17 x 5 = 85 yr
Present age of all the members of the family = 85 + 3 x 5 = 100 yr
Let the age of the child = N yr
Present avrage age of family = (100 + N) / 6
[At present total number of members = 5 + 1 = 6]
17 = 100N / 6
? 102 = 100 + N
? N = 2 yr
Correct Answer: ? 1.58
Explanation:
Number of oranges bought by the person
= 36/1 + 36/1.50 + 36/1.80 + 36/2 + 36/2.25
= 36 + 24 + 20 + 18 + 16
= 114
Total expenditure = 36 x 5 = ? 180
Thus, average price of each orange
= ? 180/114
= ? 1.58
Correct Answer: 152/3
Explanation:
According to the question,
a + b + c = 11 x 3 = 33 ......(i)
c + d + e = 17 x 3 = 51 ...........(ii)
e + f = 22 x 2 = 44 ........... (iii)
e + c = 17 x 2 = 34 ..........(iv)
From Eqs. (ii) and (iv), we get
34 + d = 51
or d = 17 ....(v)
Now, by adding Eqs. (i), (iii) and (v), we get
a + b + c + d + e + f = 33 + 44 + 17 = 94
? Average of a, b, c, d, e and f = 94/6
= 47 / 3
= 152/3
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