Question

find the list that contains all odd numbers.
12, 20, 56, 91, 15, 33
91, 33, 15, 27, 43, 71
43, 33, 36, 12, 27, 17
50, 85, 5, 10, 15, 20
select an answer.
which set of numbers contains two composite numbers and one prime number?
a) 12, 2, 31
b) 1, 5, 40
c) 55, 23, 12
d) 53, 41, 19
a
b
c
d

Explanation:

Step1: Recall odd - number definition

An odd number is not divisible evenly by 2.

Step2: Check first list

In 12, 20, 56, 91, 15, 33, 12, 20, 56 are even.

Step3: Check second list

In 91, 33, 15, 27, 43, 71, all numbers are not divisible evenly by 2.

Step4: Check third list

In 43, 33, 36, 12, 27, 17, 36 and 12 are even.

Step5: Check fourth list

In 50, 85, 5, 10, 15, 20, 50, 10, 20 are even.

Step6: Recall prime - composite definition

A prime number has only 1 and itself as factors. A composite number has more than two factors.

Step7: Check option a

In 12, 2, 31, 12 is composite, 2 and 31 are prime.

Step8: Check option b

1 is neither prime nor composite, 5 is prime, 40 is composite.

Step9: Check option c

55 is composite (55 = 5×11), 23 is prime, 12 is composite (12 = 2×6 = 3×4).

Step10: Check option d

53, 41, 19 are all prime.

Answer:

First question: 91, 33, 15, 27, 43, 71
Second question: C. 55, 23, 12