We need to find what is the lowest positive integer which gives a remainder of 5 when divided by any of the numbers 6, 7, and 8Theory: Dividend = Divisor*Quotient + RemainderLet's solve the problem using two methods
Method 1: SubstitutionLet's take each option and check if it gives 5 as remainder when divided by 6, 7 and 8.
Before we check the option choices we can use some logic to reduce the number of options to check.
Now, we know that any multiple of 6 and 8 will always be an even number.
And the number which we are looking for is (a multiple of 6 or 8) + 5
=> The number will be Even (because of multiple of even number) + Odd (because of 5) = Odd
So, we can eliminate all Even answer choices.
=> B and D are
OUT. Now lets check A, C, E
A. 153153 when divided by 6 gives 3 remainder =>
OUTC. 163153 when divided by 6 gives 1 remainder =>
OUTE. 173 -> Will be the answer as all other are out
173 when divided by 6 gives 5 as remainder
173 when divided by 7 gives 5 as remainder
173 when divided by 8 gives 5 as remainder
So,
Answer will be EMethod 2: AlgebraSince the number gives 5 remainder when divided by 6, 7 and 8 that means that the number can be written as
6x + 5, 7y + 5, 8z + 5, where x, y , z are non-negative integers
=> The number is 5 more than the multiples of 6, 7, 8
=> The number is 5 more than the LCM(6,7,8)
(
Watch this video to learn
How to Calculate LCM of 2 or more numbers)
=> The number is 5 more than 168 = 168+5 = 173
So,
Answer will be EHope it helps!
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