H.C.F and L.C.M Aptitude Test Paper 2

Answer: A

Explanation:

Let the numbers be 27x and 27y.

Then, 27x + 27y = 216
27 (x+ y) = 216
(x + y) = 216/27
X + y = 8

co-prime numbers with sum 8 are (1, 7) and (3, 5).

Therefore we can say that the required numbers are (27 x1, 27 x 7) and (27 x 3, 27x 5), i.e. (27, 189) and (81, 135).
Out of the above two answers, the given one in the answer is the pair (27, 189).

Answer: D

Explanation:

Let the two numbers are 15x and 11x
HCF = x
x = 13
Therefore, the numbers are (15 x 13 and 11 x 13), i.e. 195 and 143.

Answer: A

Explanation:

Take the difference between two numbers

376 - 358 = 18;
376 - 334 = 42;
358 - 334 = 24;

By taking the HCF of 18, 42, 24.

18 = 2 x3 x 3
42 = 2 x 3 x 7
24 = 2 x 2 x 2 x 3
HCF = 2 x 3 = 6

Hence the required number is 6.

Answer: B

Explanation:

Firstly find the LCM of 36, 40, and 48

LCM = 2 x 2 x 2 x 2 x 3 x 3 x 5 = 720 seconds

Hence, after 720 seconds or 12 minutes three bells will toll together.

Answer: C

Explanation:

Apply Formula: HCF x LCM = first number x Second number 11 x 7700 = 275 x second number