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The number of pairs lying between 40 and 100 with their H.C.F as 15 is:
The number of pairs lying between 40 and 100 with their H.C.F as 15 is:
1). 3
2). 4
3). 5
4). 6
1). 3
2). 4
3). 5
4). 6
This Question has 2 answers.
Numbers with H.C.F 15 must contain 15 as a factor.
Multiples of 15 between 40 and 100 = 45, 60, 75 and 90
Number of pairs with H.C.F 15 are (45, 60), (45, 75)(60, 75) and (75, 90)
H.C.F of (60, 90) is 30 and that of (45, 90) is 45.
∴ The number of such pairs is 4.Only 4 Pairs (45, 60), (45, 75)(60, 75) and (75, 90)
Hence Answer is : 4
Hence Answer is : 4
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