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- Question
If the average height of boys in a hall is 180 cm and that of girls is 150 cm. If the average height of the gathering is 165 cm, then find the number of girls present in the hall if the number of boys present in the hall are 78 ?
Options- A. 56
- B. 64
- C. 87
- D. 78
- Correct Answer
- 78
ExplanationUsing Trial and error method,
we get the number of girls in the hall = 78
- 1. If x = ?3 + ?2 , then the value of (x + 1/x) is
Options- A. 2
- B. 3
- C. 2?2
- D. 2?3 Discuss
- 2. The banker's gain on a certain sum due 2 1/ 2 years hence is 2/23 of the banker's discount on it for the same time and at the same rate. Find the rate percent?
Options- A. 5%
- B. 4%
- C. 8%
- D. 6% Discuss
- 3. A man 2 m high, walks at a uniform speed of 6 m/min away from a lamp post, 5 m high. Find the rate at which the length of his shadow increases .
Options- A. 4 m/min
- B. 8 m/min
- C. 9m/min
- D. 14 m/min Discuss
- 4. Ravi and Kumar are working on an assignment. Ravi takes 6 hours to type 32 pages on a computer, while Kumar takes 5 hours to type 40 pages. How much time will they take, working together on two different computers to type an assignment of 110 pages?
Options- A. 7 hours 30 minutes
- B. 8 hours
- C. 8 hours 15 minutes
- D. 8 hours 25 minutes Discuss
- 5. The highest score in an inning was 3/11 of the total score and the next highest was 3/11 of the remainder. If the score differ by 18, find the total score.
Options- A. 244
- B. 242
- C. 294
- D. 255 Discuss
- 6. A is two years older than B who is twice as old as C. If the total of the ages of A, B and C be 27, then how old is B?
Options- A. 7
- B. 8
- C. 9
- D. 10
- E. 11 Discuss
- 7. The fourth proportional to 5, 8, 15 is:
Options- A. 18
- B. 24
- C. 19
- D. 20 Discuss
- 8. If a 2 + b 2 = 234 and ab = 108, find the value of (a + b) / (a - b).
Options- A. 10
- B. 8
- C. 5
- D. 4 Discuss
- 9. How much does a watch lose per day, if its hands coincide every 64 minutes?
Options- A.
32 8 min. 11 - B.
36 5 min. 11 - C. 90 min.
- D. 96 min. Discuss
- 10. 9873 + x = 13200, then x is?
Options- A. 3327
- B. 3237
- C. 3337
- D. None of these Discuss
More questions
Correct Answer: 2?3
Explanation:
Given , X = ?3 + ?2
? 1/x = 1/(?3 + ?2)
Now Multiply and Divide by (?3 - ?2) in 1/x.
After multiply and divide, we will get
1/x = (1/(?3 + ?2)) X (?3 - ?2) /(?3 - ?2)
[rationalising]
? 1/x = ?3 - ?2/3 - 2
? x + 1/x = ?3 + ?2 + ?3 - ?2 = 2?3
Correct Answer: 6%
Explanation:
Rate percent = 100 x 2/5/ [ 3/(23 - 3)] = 6%
Correct Answer: 4 m/min
Explanation:
Let us draw a figure as per given question.
Let AB = 5 meter and CD = 2 meter be the heights of a lamp post and the men respectively.
At any time t BD = x meter and shadow of man ED = y meter.
Then, dx/dt = 6 m/min
Now, right triangles ABE and CDE are similar, then
AB/CD = BE/DE
? 5/2 = (x + y)/y
? 5y = 2x + 2y
? 5y - 2y = 2x
? 3y = 2x
? 3 dy/dt = 2 dx/dt
? 3 dy/dt = 2 x 6
? dy/dt = 2 x 6 / 3
? dy/dt = 2 x 2 = 4
Hence, length of his shadow increase at the rate of 4 m/min.
Correct Answer: 8 hours 15 minutes
Explanation:
| Number of pages typed by Ravi in 1 hour = | 32 | = | 16 | . |
| 6 | 3 |
| Number of pages typed by Kumar in 1 hour = | 40 | = 8. |
| 5 |
| Number of pages typed by both in 1 hour = | ❨ | 16 | + 8 | ❩ | = | 40 | . |
| 3 | 3 |
| ∴ Time taken by both to type 110 pages = | ❨ | 110 x | 3 | ❩ | hours |
| 40 |
| = 8 | 1 | hours (or) 8 hours 15 minutes. |
| 4 |
Correct Answer: 242
Explanation:
Let total score = N.
Then, the highest score = 3N/11.
Remainder = (N - 3N/11) = 8N/11
Next highest score = 3/11 of 8N/11 = 24N/121
According to the question,
(3N/11) - (24N/121) = 18
? 33N - 24N = 18 x 121
? 9N = 18 x 121
? N = (18 x 121)/9 = 242
Correct Answer: 10
Explanation:
∴ (2x + 2) + 2x + x = 27
⟹ 5x = 25
⟹ x = 5.
Hence, B's age = 2x = 10 years.
Correct Answer: 24
Explanation:
Then, 5 : 8 : 15 : x
⟹ 5x = (8 x 15)
| x = | (8 x 15) | = 24. |
| 5 |
Correct Answer: 5
Explanation:
We know that, (a + b)2 = a2 + b2 + 2ab
= 234 + 2 x 108 = 450
(a - b)2 = a2 + b2 - 2ab
= 234 - 2 x 108 = 18
? (a + b)2/(a - b)2 = 450/18 = 25
? [(a + b)/(a - b)]2 = 25
? (a + b)/(a - b) = ?25 = 5
Correct Answer:
| 32 | 8 | min. |
| 11 |
Explanation:
| 60 min. spaces are covered in | ❨ | 60 | x 60 | ❩min. | = 65 | 5 | min. |
| 55 | 11 |
| Loss in 64 min. = | ❨ | 65 | 5 | - 64 | ❩ | = | 16 | min. |
| 11 | 11 |
| Loss in 24 hrs = | ❨ | 16 | x | 1 | x 24 x 60 | ❩min. | = | 32 | 8 | min. |
| 11 | 64 | 11 |
Correct Answer: 3327
Explanation:
x = 13200 - 9873 = 3327
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