Answer:

• 8:7 (eight is to seven)

Step-by-step explanation:

Prime numbers less than 20:

2,3,5,7,11,13,17,19

Composite numbers less than 15:

4,6,8,9,10,12,14

Ratio of the number of prime numbers less than 20 to the number of composite numbers less than 15: 8:7

Prime numbers less than 20 : 19, 17, 13, 11, 7, 5, 3, 2

Number of prime numbers less than 20: 8

Composite numbers less than 15: 14, 12, 10, 9, 8, 6, 4

Number of Composite numbers less than 15: 7

Therefore, ratio of the prime numbers less than 20 to the composite numbers less than 15 is

8 : 7