If a and b are positive integers, is 3(a^2)b divisible by 60?
1) a is divisible by 10
2) b is divisible by 18
OA to follow shortly but I'll tell you that it isn't E!!
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hard factorisation question
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stubbornp
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stmt 1: a is divisible by 10
Min value for A is 10..
3(10)^2.b/60 = 300*b/60 = 5*b-----sufficient
Stmt 2:
b is divisible by 18
but we need atleast one factor of 5..---insufficient
A is answer
Min value for A is 10..
3(10)^2.b/60 = 300*b/60 = 5*b-----sufficient
Stmt 2:
b is divisible by 18
but we need atleast one factor of 5..---insufficient
A is answer
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logitech
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if something is divisible by 60: you need to have 2x2x3x5 prime numbers in itjsl wrote:If a and b are positive integers, is 3(a^2)b divisible by 60?
1) a is divisible by 10
2) b is divisible by 18
OA to follow shortly but I'll tell you that it isn't E!!
1) a is divisible by 10 means it has 2x5
the question can be simplified to is a^2b divisible by 20 ( 2x2x5)
so 1 is sufficient since a^2 will have 2x2x5x5 SUF
2) INSUF because 18 has no 5 as a prime factor
A
LGTCH
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