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If the average (arithmetic mean) of the four numbers \(3, 15, 32,\) and \(N + 1\) is \(18,\) then \(N =\)

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Re: If the average (arithmetic mean) of the four numbers \(3, 15, 32,\) and \(N + 1\) is \(18,\) then \(N =\)

by Brent@GMATPrepNow » Tue Aug 17, 2021 6:20 am
M7MBA wrote: ↑
Sun Aug 15, 2021 3:17 pm
 If the average (arithmetic mean) of the four numbers \(3, 15, 32,\) and \(N + 1\) is \(18,\) then \(N =\)

(A) 19
(B) 20
(C) 21
(D) 22
(E) 29

Answer: C

Source: Official Guide
The average (arithmetic mean) of the four numbers 3, 15, 32, and (N + 1) is 18
So, (sum of all 4 numbers)/4 = 18
Multiply both sides by 4 to get: sum of all 4 numbers = 72
This means that 3 + 15 + 32 + (N+1) = 72
Simplify: N + 51 = 72
Solve to get: N = 21

Answer: C
Brent Hanneson - Creator of GMATPrepNow.com
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