Discussion
Home ‣ Aptitude ‣ Permutation and Combination See What Others Are Saying!
- Question
- How many numbers can be formed from 1, 2, 3, 4, 5, ( without repetition), when the digit at the unit's place must be greater than that in the ten's place?
Options- A. 54
- B. 60
- C. 51/3
- D. 2 x 4!
- Correct Answer
- 60
ExplanationThe digit in the unit's place should be greater than that in the tens' place.
Hence, if digit 5 occupies the unit place, then remaining four digits need not to follow any order,hence required number = 4!
However, if digit 4 occupies the unit place then 5 cannot occupy the ten;s position. Hence, digit at the ten's place and it will be filled by the digit 1, 2 or 3. This can happen in 3 ways. The remaining 3 digit can be filled in the remaining three place in 3! ways.
Hence, in all, we have (3 x 3!) numbers ending in 4. Similarly, if we have 3 in the unit's place and it will be either 1 or 2. this can happen in 2 ways. Hence, we will have (2 x 3! ) number ending in 3 . Similarly, we can find that there will be 3! numbers ending in 2 and no number with 1. Hence, total number of numbers
= 4! + (3) x 3! + (2 x 3!) + 3!
= 4! + 6 x 3! = 24 + (6 x 6) = 60 - 1. In a race of 600 m, A can beat B by 60 m and in a race of 500 m, B can beat C by 50 m. By how many meters will A beat C in a race of 400 m?
Options- A. 364 m
- B. 254 m
- C. 324 m
- D. 354 m Discuss
- 2. 36.98276421 x 21.00002 =?
Options- A. 775
- B. 785
- C. 800
- D. 805 Discuss
- 3. In the figure, BD and CD are angle bisectors of ? ABC and ? ACE, respectively. Then ? BDC is equal to :
Options- A. ?BAC
- B. 2?BAC
- C. 1 ?BAC 2
- D. 1 ?BAC 3 Discuss
- 4. What is the unit digit in {(6374)1793 x (625)317 x (341491)}?
Options- A. 0
- B. 2
- C. 3
- D. 5 Discuss
- 5. How many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?
Options- A. 25
- B. 30
- C. 40
- D. 45 Discuss
- 6. Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:
Options- A. 2 : 3
- B. 4 : 3
- C. 6 : 7
- D. 9 : 16 Discuss
- 7. A train travelling at a speed of 75 mph enters a tunnel 3½ miles long. The train is ¼ mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
Options- A. 2.5 min
- B. 3 min
- C. 3.2 min
- D. 3.5 min Discuss
- 8. Which one of the following numbers is completely divisible by 45?
Options- A. 181560
- B. 331145
- C. 202860
- D. 2033555
- E. None of these Discuss
- 9. 7589 -? = 3434
Options- A. 4242
- B. 4155
- C. 1123
- D. 11023
- E. None of these Discuss
- 10. Find the angle between minute hand hour hand at 11 : 50 AM
Options- A. 55°
- B. 22.5°
- C. 15°
- D. None of these Discuss
More questions
Correct Answer: 324 m
Explanation:
Clearly, if A runs 600 meters, B runs = 540 m.
? If A runs 400 m, B runs = 540 x 400 / 600 = 540 x 4 / 6 = 90 x 4 = 360 m
Again, when B runs 500 m, C runs = 450 m
? When B runs 360 m, C runs = 450 x 360 / 500 = 45 x 36 / 5 = 9 x 36 = 324 m.
? A beats C by 400 - 324 = 76 m.
Correct Answer: 775
Explanation:
36.98276421 x 21.00002
Using nearest value in whole number for 36.9827421 is 37 and 21.0002 is 21
? 37 x 21 = 777 ? 775
Correct Answer: 1 ?BAC 2
Explanation:
Correct Answer: 0
Explanation:
Unit digit in (6374) 1793 = Unit digit in (4) 1793
= Unit digit in [(42)896 x 4]
= Unit digit in (6 x 4) = 4
Unit digit in (625)317 = Unit digit in (5)317 = 5
Unit digit in (341)491 = Unit digit in (1)491 = 1
Required digit = Unit digit in (4 x 5 x 1) = 0.
Correct Answer: 30
Explanation:
| Speed of the train relative to man | = (63 - 3) km/hr | |||||||
| = 60 km/hr | ||||||||
|
||||||||
|
||||||||
| ∴ Time taken to pass the man |
|
|||||||
| = 30 sec. |
Correct Answer: 4 : 3
Explanation:
Let us name the trains as A and B. Then,
(A's speed) : (B's speed) = √b : √a = √16 : √9 = 4 : 3.
Correct Answer: 3 min
Explanation:
| Total distance covered |
|
|||||||||
|
| ∴ Time taken |
|
|||||||
|
||||||||
|
||||||||
| = 3 min. |
Correct Answer: 202860
Explanation:
45 = 5 x 9, where 5 and 9 are co-primes.
Unit digit must be 0 or 5 and sum of digits must be divisible by 9.
Among given numbers, such number is 202860.
Correct Answer: 4155
Explanation:
Let 7589 -x = 3434
Then, x = 7589 - 3434 = 4155
Correct Answer: 55°
Explanation:
At 11 : 50 A.M. from the formula here P = 11 and Q = 50 so required angle is 11 x 50/2 - 30 x 11 = 275 - 330 = -55 or ignoring the negative sign the required angle is 55°
Comments
There are no comments.More in Aptitude:
Programming
Copyright ©CuriousTab. All rights reserved.