Discussion
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- Question
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm3, then the weight of the pipe is:
Options- A. 3.6 kg
- B. 3.696 kg
- C. 36 kg
- D. 36.9 kg
- Correct Answer
- 3.696 kg
Explanation
External radius = 4 cm,Internal radius = 3 cm.
Volume of iron = ❨ 22 x [(4)2 - (3)2] x 21 ❩cm3 7 = ❨ 22 x 7 x 1 x 21 ❩cm3 7 = 462 cm3. ∴ Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
- 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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