The average (arithmetic mean) of 11 numbers is 10. When one number is eliminated, the average of the remaining numbers

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VJesus12: Legendary Member; Posts: 2276; Joined: Sat Oct 14, 2017 6:10 amFollowed by: 3 members

by VJesus12 » Sat May 30, 2020 3:21 pm

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The average (arithmetic mean) of 11 numbers is 10. When one number is eliminated, the average of the remaining numbers is 9.3. What is the eliminated number?

A. 14
B. 15
C. 16
D. 17
E. 18

[spoiler]OA=D[/spoiler]

Source: Manhattan GMAT

Source: Beat The GMAT — Problem Solving | Sat May 30, 2020 3:21 pm

orthodoxparadox: Junior | Next Rank: 30 Posts; Posts: 15; Joined: Sat May 30, 2020 10:48 pm

Re: The average (arithmetic mean) of 11 numbers is 10. When one number is eliminated, the average of the remaining numbe

by orthodoxparadox » Sat May 30, 2020 11:28 pm

We know that if mean of $n$ numbers is $M$ , then sum of the numbers is $n\ \cdot\ M$

So, sum of the 11 numbers is $11\ \cdot\ 10\ =\ 110$

After removing one number, sum of remaining numbers is $9.3\ \cdot\ 10\ =\ 93$

So the removed number is $110\ -\ 93\ =\ 17$ D

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