Question

The L.C.M. of two numbers is 4800 and their G.C.M. is 160. If one of the numbers is 480, then the other
number is:
(a) 1600
(b) 1800
(c) 2200
(d) 2600
(e) None of these

Answer 1

xy = 4800 x 160 = 768000

x = 480

y = 768000/480 = 1600

Answer 2

answer : option (a) 1600

explanation : Let unknown number is x

HCF of 480 and x is 160

so, x = 160k and 480 = 160 × 3

where k is non divisible by 3.

again, LCM of 480 and x = 4800

or, LCM of 480 and 160k = 4800.

or, 160 × 3 × k = 4800

or, k = 10

hence, unknown number is x = 160k = 1600

option (a) is correct