Let's say S = {a, b, c, d, e}. We want to know if all the numbers in the sequence are divisible by 5.
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What does A tell us?
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Let n be some positive integer; a + b + c + d + e = 5n
This is one where we are better off using counterexamples
Let's take the following integers (each with remainder 1) as an option:
a = 1
b = 6
c = 11
d = 16
e = 21
Note that the sum of these numbers is divisible by 5, but none of a,b,c,d,e are themselves divisible by 5.
But we could consider an alternative example:
a = 5
b = 10
c = 15
d = 20
e = 25
This works, so we can establish that Statement A is insufficient.
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What does B tell us?
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Product is divisible by 5 but not by 10; this tell us none of the numbers in the sequence are even.
Algebraically, this says to us that, for some integer m, a * b * c * d * e = 5m, where none of a, b, c, d, e is even.
This is one where we can build a counterexample.
Suppose the following is true:
a = 1
b = 3
c = 5
d = 7
e = 9
The product of these is 945, which is divisible by 5 but not 10; only c is divisible by 5
But we could also consider the alternative here:
a = 5
b = 15
c = 25
d = 35
e = 45
The product of these numbers is a big number divisible by 5 but not 10; and each of a,b,c,d,e is divisible by 5
So Statement B is insufficient
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What if they're both true?
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We can repurpose our last example here:
a = 5
b = 15
c = 25
d = 35
e = 45
Here, each of the numbers of the sequence is divisible by 5 and odd, so it follows that the product is divisible by 5 (but not 10) and the sum of the sequence is divisible by 5
But we can come up with another counterexample here:
a = 1
b = 5
c = 15
d = 3
e = 11
Well, turns out the sum and the product of these are divisible by 5 (but not 10), but only b and c are divisible by 5.
So the statements together are insufficient
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The answer is E