If T is a list of consecutive integers in increasing order

Question

If T is a list of consecutive integers in increasing order, what is the sum of integers in T?

(1) The difference between the last integer in T and the first integer in T is 100.
(2) The fourth integer in T is -6

Bunuel · Accepted Answer

If T is a list of consecutive integers in increasing order, what is the sum of integers in T?

(1) The difference between the last integer in T and the first integer in T is 100. This implies that there are 101 integers in the list. T could be any list of 101 consecutive integers. For example, {0, 1, 2, ..., 100} or {1, 2, 3, ..., 101}. Not sufficient.

(2) The fourth integer in T is -6. This implies that the first integer is -9. We don't know how many integers are there in the list, hence cannot get the sum. Not sufficient.

(1)+(2) We know that the first integer is -9 and that there are total of 101 integers in the list: T = {-9, -8, -7, -6, ..., 91}. We can get the sum. Sufficient.

Answer: C.

Hope it's clear.

vikrantgulia · Answer

1) The difference between any two integer is 100.So,Let first number could be -1,0,or,1 then last number would be 99,100,or 101 and each series give different sum. Hence, Not Sufficient.

2) fourth integer is -6 .so first integer is n+3=-6 i.e -9 but we don't know the number of of terms in T. that sum of 100 terms of sum of 200 terms. Not sufficient

1) and 2) together we know that first integer is -9 and difference of last integer and first integer is 100. So we definitely get a sum.Hence C is the correct answer

australia123 · Answer

Banuel you gave the solution on all thread, so a lot of thanks of you...

GloryBoy92 · Answer

Hi Burnel, why is the first integer -9?

Inten21 · Answer

Mind if I answer it for you! So the statement says that "The fourth integer in T is -6." Trace it back to get the first integer in the series. -9 <1st> // -8 <2nd> // -7 <3rd> // and then -6 <4th, which is given> Hope it is clear now.

Basshead · Answer

To determine the sum of integers in T, we need to do the number of integers and either the first integer or the last integer in the set.

(1) This gives us the number of integers, but we don't know the first integer or last integer in the set. INSUFFICIENT.

(2) Given the fourth integer, we can determine the first integer. However, we don't know the number of integers in the set. INSUFFICIENT.

(1&2) Combined, we can determine the sum. SUFFICIENT.

Answer is C.

bumpbot · Answer

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If T is a list of consecutive integers in increasing order

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If T is a list of consecutive integers in increasing order

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