(b) 26
Multiple Choice Questions (MCQs)
8. The number of primes between 1 and 100 is
(a) 20
(c) 25
(d) 27
9. Which of the following is a pair of co-primes?
(a) 20, 25
(b) 18,35
(c) 15, 63
(d) 28,81
10. Which of the following is a pair of twin primes
between 50 and 70 ?
(a) 51, 53
(b) 57, 59
(c) 59, 61
(d) 63, 65
Tests for Divisibility
Answers
Answer :
Question 8
Question 8 Ans = 25
Nisha smart study
Answer:
Q8 25
Q9
Answer :
Step-by-step explanation:
A Co-prime number is a set of numbers or integers which have only 1 as their common factor i.e. their highest common factor (HCF) will be 1.
a) Factors of 18 = 1, 2, 3, 6, 9,18
Factors of 35 = 1, 5, 7, 35
Common factor of 18 and 35 = 1
Since both have only one common factor, i.e., 1, therefore, they are co-prime numbers.
(b)Factors of 15 = 1, 3, 5,15
Factors of 37 = 1, 37
Common factor of 15 and 37 = 1
since both have only one common factor, i.e., 1, therefore, they are co-prime numbers.
(c)Factors of 30 = 1, 2, 3, 5, 6, 15, 30
Factors of 415 = 1, 5, 83, 415
Common factor of 30 and 415 = 1,5
Since both have more than one common factor, therefore, they are not co-prime numbers
(d)Factors of 17 = 1, 17
Factors of 68 = 1, 2, 4, 17, 34, 86
Common factor of 17 and 68 = 1, 17
Since, both have more than one common factor, therefore, they are not co-prime numbers
(e)Factors of 216 = 1, 2, 3, 4, 6, 8, 36, 72, 108,216
Factors of 215 = 1, 5, 43, 215
Common factor of 216 and 215 = 1
Since, both Have only one common factor, i.e , 1 , therefore they are co-prime numbers.
(f)Factors of 81 = 1, 3, 9, 27, 81
Factors of 16 = 1, 2, 4, 8, 16
Common factor of 81 and 16 = 1
Since both have only one common factor, i.e., 1, therefore, they are co-prime numbers.