Question

Which of the following pairs of numbers is co – prime ?

A. (17,35)

B. (10,16)

C. (20,24)

D. (31,64)

Answer 1

Hint: Find the factors of both the numbers and check if they satisfy the needs for being a pair of co – primes . They will be co – primes if there is no common factor except 1 in both of them.

Complete step-by-step answer:

17 and 35 have prime factors 1 , 17 and 1 , 5 , 7 respectively. Thus there is no other common factor other than 1. Therefore they are co – primes . (10,16) , (20,24) , (31,64) each have common primes factors other than 1 thus these are not co – primes.

Therefore, the correct answer is option A.

Note:
In these types of questions remember to only look for prime factors while finding factors of each number. The concept of co – primes must be properly understood to solve such types of questions.