Question

let p, q be the number of natural number Which are less than or equal to 20and are prime and composite respectively than 20- p -q

Answer 1

Step-by-step explanation:

TOTAL NO. OF PRIME NO. = 8

TOTAL NO. OF COMPOSITE NO. = 11

THEREFORE 20-P-Q = 20-8-11

ANSWER IS 1

Answer 2

Concept:

Prime and composite numbers.

Prime numbers: Prime numbers are those numbers that have only two factors i.e., 1 and the number itself. Example: 2, 3, 5 etc.

Composite numbers: Composite numbers are those numbers that have more than two factors. Eg: 6, 8, 9, etc.

Answer and explanation:

Total natural numbers = 20

Number of prime numbers less than or equal to 20, p = {2, 3, 5, 7, 11, 13, 17, 19} = 8

Number of composite numbers less than or equal to 20, q = {1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20} = 12

∴ 20 - p - q = 20 - 8 - 12 = 0

Hence, 20 - p - q = 0.

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