Bunuel wrote:
In a series of twenty consecutive integers, the sum of the first two integers is 37. What is the sum of the last three integers in the set?
A 107
B 108
C 109
D 110
E 111
In a set of consecutive integers, the sum of the first two is 37
(1) First integer, \(x\)?
\(x + (x+1)=37\)
\(2x+1=37\)
\(x=18\)
(2) Last integer?
If \(x\) is the first integer, and there are 20 integers total, then there are 19 more
Add 19 to \(x=18\) (Consecutive = +1 for each integer in the set.)
\(18+19=37\)
If not sure, use a simpler example: There are 4 consecutive integers in the set.
\(x=18\). List them. 18, 19, 20, 21
There are
4 integers, but we need only
+3 added to \(x=18\) to find the last integer.
20 integers in this set, but add only 19 to the first integer. \(18+19=37\)
(3) Sum of last three integers?
Last three integers: 37, 36, 35
Mentally add the units digits.
Units digit = 8
(Or, 37 + 36 + 35 = 108)
Answer B
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74% (01:23) correct 
