# Problems on LCM and HCF Part 2

## Problems on LCM and HCF Part 2

21.
The greatest possible length which can be used to measure exactly the lengths 7 m, 3 m 85 cm, 12 m 95 cm is:
 A. 15 cm B. 25 cm C. 35 cm D. 42 cm
Explanation:
Required length = H.C.F. of 700 cm, 385 cm and 1295 cm = 35 cm.
22.
Three numbers which are co-prime to each other are such that the product of the first two is 551 and that of the last two is 1073. The sum of the three numbers is:
 A. 75 B. 81 C. 85 D. 89
Explanation:
Since the numbers are co-prime, they contain only 1 as the common factor.
Also, the given two products have the middle number in common.
So, middle number = H.C.F. of 551 and 1073 = 29;
 First number = 551 = 19;    Third number = 1073 = 37. 29 29
Required sum = (19 + 29 + 37) = 85.
23.
Find the highest common factor of 36 and 84.
 A. 4 B. 6 C. 12 D. 18
Explanation:
36 = 22 x 32
84 = 22 x 3 x 7
H.C.F. = 22 x 3 = 12.
24.
Which of the following fraction is the largest ?
A.
 7 8
B.
 13 16
C.
 31 40
D.
 63 80