Friday, February 12, 2010

The statement ';If x is divisible by 8, then it is divisible by 6'; is false if x equals a b c ord?

a6


b14


c 32


d 48


I know the answer is 32 but how do you get thatThe statement ';If x is divisible by 8, then it is divisible by 6'; is false if x equals a b c ord?
32 is the only option divisible by 8, but not by 6.The statement ';If x is divisible by 8, then it is divisible by 6'; is false if x equals a b c ord?
32 is the only choice divisible by 8 and not by 6.


To get a false conclusion you need a true


hypothesis and a false inference.


32 is the only choice that provides that.
If we assume that x is divisible by 8 then, then x is definitely not divisible by 6 for it to have any of the values of a,b,c,d. (anyways, x would be one of c or d; since a and b are not divisible by 8) Hence this definitely makes x=32
remember those divisibility rules?





6 divides a number if 2 and 3 both divide it


- 2 if it is even


- 3 if the sum of the digits is a multiple of 3


8 divides a number if the last 2 digits are divisible by 8





You could test all the numbers and find it that way also





While overly complicated for this problem, it is another way to look at problems of this type

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