Question

What is the ratio of the number of prime numbers to the number of composite numbers between $1$and$30$ with $1$and$30$ inclusive?

Answer 1

Step 1: To identify the prime numbers and composite numbers between $1$and $30$ ($1$and $30$ inclusive)

Prime numbers: $2,3,5,7,11,13,17,19,23,29=10$

Composite numbers: $1,4,6,8,9,10,12,14,15,16,18,20,21,22,24,25,26,27,28,30=20$

Step 2: To find the ratio.

The ratio of prime numbers to composite numbers between $1$and $30$ is $=\frac{10}{20}=\frac{10÷10}{20÷10}=\frac{1}{2}=1:2$

Therefore, the ratio of the number of prime numbers to the number of composite numbers between $1$and $30$ ($1$and$30$ inclusive) is $1:2$.