The average (arithmetic mean) of 6 consecutive integers is 18½. What

Question

The average (arithmetic mean) of 6 consecutive integers is 18½. What is the average of the 5 smallest of these integers?

(A) 12 ½ 
(B) 15
(C) 16
(D) 17 ½ 
(E) 18

pushpitkc · Answer

The average of even number of consecutive integers is nothing but the 
average of the middle two numbers - number 3(x) and number 4(y)
The average of odd number of consecutive integers is the middle integer.

Therefore,  \frac{x+y}{2}= 18.5 => x+y = 37  where x = 18 and y = 19
Hence, the third element must be the average of the 5 smallest integers, which is  18(Option E)

niks18 · Answer

Let the numbers be x-2, x-1, x, x+1, x+2 & x+3

Sum of six numbers  = 6x+3= \frac{37}{2}*6

=>x=18

if largest no i.e x+3 is removed then median of the remaining 5 consecutive number,  x=Average =18

Option  E

Abhishek009 · Answer

n + (n +1) + (n +2) + (n +3) + (n +4) + (n +5) = 18½*6 = 111

Or,  n + (n +1) + (n +2) + (n +3) + (n +4) + (n +5) = 111

Or,  6n + 15 = 111

Or, 6n = 96

So, n = 16

Average of the 5 smallest of these integers =  \frac{16 + 17 + 18 + 19 + 20}{5}   = \frac{90}{5} = 18 
  
Thus, answer will be (E)

generis · Answer

Approach #1: (First Term + Last Term) ÷ 2

In an arithmetic progression, consecutive integers included, the mean equals

\frac{FirstTerm+LastTerm}{2}   
Use that to find the smallest integer

The six consecutive integers are 
x, (x+1), (x+2), (x+3), (x+4), (x+5)
 
Average (mean)=  \frac{FirstTerm+LastTerm}{2}  
 \frac{x+(x+5)}{2}=18.5 
 2x + 5 = 37 
 2x = 32 ,  x = 16 = first term

Average of first  5  terms:  \frac{FirstTerm+LastTerm}{2}  
A =  \frac{16+20}{2}= 18

OR, in an AP {16, 17, 18, 19, 20}:
median = mean = 18

ANSWER E

Approach #2: Standard Average 
 \frac{S}{n}=A 
Use the 6 terms defined in terms of x, above

\frac{6x + 15}{6} = 18.5 
  6x + 15 = 111 
 6x = 96  ,  x = 16 = first term

First  five  terms: 16, 17, 18, 19, 20
Average:  \frac{16+17+18+19+20}{5}=\frac{90}{5}=18

ANSWER E

akadiyan · Answer

Average of 6 numbers is 18 1/2

So sum of 6 consecutive numbers is 111.

Now lets find the smallest number - x

Since the numbers are consecutive - 5 numbers after x will all add up to 15 (x+1, x+2...x+5)
6X + 15 = 111
6X = 96
X=16

5 Smallest numbers are 16, 17, 18, 19, 20.

Average of 5 smallest number = Average of odd number is the middle integer in the list, in our list its 18.

Ans:   E

KarishmaB · Answer

When you remove the largest element of the consecutive integers list, the mean moves down by 0.5. So mean of 5 smallest integers will be 18. This post discusses this and other related concepts: https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2015/0 ... -the-gmat/

ScottTargetTestPrep · Answer

We can let the first integer = x and the sixth integer = x + 5, and thus:

(x + x + 5)/2 = 18.5

2x + 5 = 37

2x = 32

x = 16

So the smallest of the 5 integers is 16, and the 5th largest is 16 + 4 = 20, so the average is:

(16 + 20)/2 = 36/2 = 18

Answer: E

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The average (arithmetic mean) of 6 consecutive integers is 18½. What

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The average (arithmetic mean) of 6 consecutive integers is 18½. What

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