Question

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

• A. $\left(14,35\right)$
• B. $\left(18,25\right)$
• C. $\left(31,93\right)$
• D. $\left(32,62\right)$

Answer 1

The correct option is B

$\left(18,25\right)$

Explanation for correct option:

Determine the pair of co-primes.

The co-primes are a pair of numbers that do not have any common factor.

The factors of $18$ are $1,2,3,6,9,\mathrm{and}18$ and the factors of $25$ are $1,5,\mathrm{and}25$.

So, the numbers $18$ and $25$ do not have any common factor.

Thus, option B: $\left(18,25\right)$ is a pair of co-primes.

Explanation for all incorrect options:

Option A : $\left(14,35\right)$

The numbers $14$ and $35$ have a common factor $7$.

Option C : $\left(31,93\right)$

The numbers $31$ and $93$ have a common factor $31$.

Option D : $\left(32,62\right)$

The numbers $32$ and $62$ have a common factor $2$.

Therefore, the correct option is B.