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If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what [#permalink]
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18 Jan 2018, 08:41
Bunuel wrote:
If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what is the average of m + 4 and n – 2 ?
(A) 9 (B) 13 (C) 14 (D) 18 (E) 26
Average of m+4 and n-2 is \(\frac{m+n+4-2}{2} = \frac{m+n}{2} + 1\) = Average of m,n + 1
It has been given that the average of 5 numbers is 9, making their sum 45. Of the 5 numbers, we know that three of the numbers total 19. So, m+n=26 Average of m and n is 13.
Therefore, the average of m+4 and n-2 is 13+1 = 14(Option C) _________________
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Re: If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what [#permalink]
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20 Feb 2018, 20:47
3 is 6 less than 9(average) & 6 is 3 less and 10 is 1 more so we got 8 less that has to be covered by m and n so average of m and n is 9+(8/2)= 13 and then m+4 and n-2 we have 2 as extra other than m &n and by dividing it with 2 we get 1 which is added to average of m & n so final answer is 14
Re: If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what [#permalink]
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09 Mar 2018, 08:33
Top Contributor
Bunuel wrote:
If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what is the average of m + 4 and n – 2 ?
(A) 9 (B) 13 (C) 14 (D) 18 (E) 26
The average (arithmetic mean) of 3, 6, 10, m and n is 9 So, (3 + 6 + 10 + m + n)/5 = 9 Multiply both sides by 5 to get: 3 + 6 + 10 + m + n = 45 Simplify: 19 + m + n = 45 Subtract 19 from both sides to get: m + n = 26
What is the average of m + 4 and n – 2 ? We get: average = [(m + 4) + (n - 2)]/2 Simplify: average = (m + n + 2)/2 Replace m + n to get: average = (26 + 2)/2 Simplify: average = (28)/2 = 14
Answer: C
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Re: If the average (arithmetic mean) of 3, 6, 10, m and n is 9, then what
[#permalink]
09 Mar 2018, 08:33