Question

Marcy found two numbers that satisfy the following rules:
● Has one prime number
● Has one composite number
● The sum of the numbers is prime
Problem

Which two numbers could be the numbers that Marcy found?

A

23 and 27

B

11 and 20

C

8 and 16

D

13 and 15

Answer 1

one is even, the other is odd if you want the sum to be prime (that is, odd)
Only B works for that

Answer 2

B

Because:

In answer A

23 and 27

Both numbers are prime.

In answer C

8 and 16

Both numbers are composite numbers.

In answer D

13 and 15

13 is prime 15 is composite, but their sum 13 + 15 = 28 is not prime.

So in answer B:

11 is prime, 20 is composte.

Their sum 11 + 20 = 31 is prime.

Answer 3

My typo.

In answer A

23 and 27

23 is prime 27 is composite, but their sum 23 + 27 = 40 is not prime.

Answer 4

A