Which of the following is a pair of co-primes?

Correct option is D

Given:

Pair of numbers (7,35) (217,651) (32,62) (198,175)

Formula Used:

Co-prime numbers are number which have one as their common factor or their HCF is 1

Solution:

Checking for common factors:

(7, 35)

7 = 1 $$\times$$​ 7

35 = 5 $$\times$$​ 7

Both have a common factor 7 or HCF 7

(217, 651)

217 = 7 $$\times$$ 31

651 = $$3 \times 7 \times 31$$

Their HCF is 217.

Not a co-prime pair

(32, 62)

32 = $$2^5$$​​

62 = $$2 \times 31$$​​

Both have HCF as 2

Not a co-prime pair

(198, 175)

198 = $$2 \times 3^2 \times 11$$​​

175 = $$5^2 \times 7$$​​

175 and 198 does not have any factor in common and their HCF is 1

Hence 175 and 198 are co-primes.