Description : The L.C.M of two numbers is 14 times their H.C.F . The sum of the L.C.M. and the H.C.F . is 600. If one number is 280 , then the other number is (a) 40 (b) 60 (c) 80 (d) 100

Description : The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is: A.1 B.2 C.3 D.5 E.None of these

Answer : Answer – B (2) Explanation – Let 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).

Description : Six bells commencing tolling together toll at intervals of 2, 3, 6, 8 , 10 and 12 seconds respectively.In 30 minutes how many times do they toll together?

Answer : Ans 1. L.C.M of 2, 4, 6, 8, 10 and 12 is 120. so, the bells will toll together after 120 seconds i.e. 2 minutes . In 30 minutes the bells toll together 30/2 + 1 times i.e. times.

Description : A gardener had a number of shrubs to plant in rows . At first he tried to plant 8, then 12 and then 16 in a row but he always had 3 shrubs left with him . On trying 7 shrubs he was left with none.Find the total number of shrubs.

Answer : Ans 3. L.C.M of 8,12,16 = 48 Now, 48 x 1 + 3 = 51 - not divisible by 7 48 x 2 + 3 = 99 - not divisible by 7 48 x 3 + 3 = 147 - not divisible by 7 Required number = 147