Question

Which of the following groups of numbers are all prime numbers? A. 2, 5, 15, 19 B. 7, 17, 29, 49 C. 2, 3, 5, 9 D. 3, 11, 23, 31

Answer 1

some prime numbers
2,3,5,7,11,13,17,19,23,29,31
just try to divide by those and if you an, then it isn't prim

A. 15/3=5 so not prime
B. 49/7=7, not prime
C. 9/3=3 not prime
D. all prime


answe ris D

Answer 2

So,

The prime numbers from 1 to 50 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.

Group A contains 15, which is a composite number (3 * 5).

Group B contains 49, which is a composite number (7 * 7).

Group C contains 9, which is a composite number (3 * 3).

Group D contains no composite numbers.  They are all prime.

Group D contains only prime numbers.