Discussion
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- Question
The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is:
Options- A. 1
- B. 2
- C. 3
- D. 4
- Correct Answer
- 2
ExplanationLet the numbers 13a and 13b.
Then, 13a x 13b = 2028
=>ab = 12.
Now, the co-primes with product 12 are (1, 12) and (3, 4).
[Note: Two integers a and b are said to be coprime or relatively prime if they have no common positive factor other than 1 or, equivalently, if their greatest common divisor is 1 ]
So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4).
Clearly, there are 2 such pairs.
- 1. The greatest number which on dividing 1657 and 2037 leaves remainders 6 and 5 respectively, is:
Options- A. 123
- B. 127
- C. 235
- D. 305 Discuss
- 2. Three number are in the ratio of 3 : 4 : 5 and their L.C.M. is 2400. Their H.C.F. is:
Options- A. 40
- B. 80
- C. 120
- D. 200 Discuss
- 3. Sum of four times a fraction and 6 times its reciprocal is 11. What is the fraction?
Options- A. 3/4
- B. 4/3
- C. 4/7
- D. 7/4 Discuss
- 4. Sum of twice a fraction and 3 times its reciprocal is 29/3. What is the fraction?
Options- A. 2/9
- B. 5/4
- C. 4/5
- D. 9/2 Discuss
- 5. The sum of a fraction and 3 times its reciprocal is 31/6. What is the fraction?
Options- A. 2/9
- B. 9/2
- C. 5/4
- D. 4/5 Discuss
- 6. A rectangular courtyard 3.78 meters long 5.25 meters wide is to be paved exactly with square tiles, all of the same size. what is the largest size of the tile which could be used for the purpose?
Options- A. 14 cms
- B. 21 cms
- C. 42 cms
- D. None of these Discuss
- 7. The L.C.M of 22, 54, 108, 135 and 198 is
Options- A. 330
- B. 1980
- C. 5940
- D. 11880 Discuss
- 8. The L.C.M of two numbers is 495 and their H.C.F is 5. If the sum of the numbers is 100, then their difference is
Options- A. 10
- B. 46
- C. 70
- D. 90 Discuss
- 9. The sum of two numbers is 528 and their H.C.F is 33. The number of pairs of numbers satisfying the above condition is
Options- A. 4
- B. 6
- C. 8
- D. 12 Discuss
- 10. Product of two co-prime numbers is 117. Their L.C.M should be
Options- A. 1
- B. 117
- C. Equal to their H.C.F
- D. cannot be calculated Discuss
Search Results
Correct Answer: 127
Explanation:
Required number = H.C.F. of (1657 - 6) and (2037 - 5)
= H.C.F. of 1651 and 2032 = 127.
Correct Answer: 40
Explanation:
Let the numbers be 3x, 4x and 5x.
Then, their L.C.M. = 60x.
So, 60x = 2400 or x = 40.
The numbers are (3 x 40), (4 x 40) and (5 x 40).
Hence, required H.C.F. = 40.
Correct Answer: 3/4
Correct Answer: 9/2
Correct Answer: 9/2
Correct Answer: 21 cms
Explanation:
3.78 meters =378 cm = 2 × 3 × 3 × 3 × 7
5.25 meters=525 cm = 5 × 5 × 3 × 7
Hence common factors are 3 and 7
Hence LCM = 3 × 7 = 21
Hence largest size of square tiles that can be paved exactly with square tiles is 21 cm.
Correct Answer: 5940
Explanation:
22 = 2 x 11
54 =
108 =
135 =
198 =
Correct Answer: 10
Explanation:
Let the numbers be x and (100-x).
Then,
=>
=> (x-55) (x-45) = 0
=> x = 55 or x = 45
The numbers are 45 and 55
Required difference = (55-45) = 10
Correct Answer: 4
Explanation:
Let the required numbers be 33a and 33b.
Then 33a +33b= 528 => a+b = 16.
Now, co-primes with sum 16 are (1,15) , (3,13) , (5,11) and (7,9).
Therefore, Required numbers are ( 33 x 1, 33 x 15), (33 x 3, 33 x 13), (33 x 5, 33 x 11), (33 x 7, 33 x 9)
The number of such pairs is 4
Correct Answer: 117
Explanation:
H.C.F of co-prime numbers is 1. So, L.C.M = 117/1 =117
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