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# If the average (arithmetic mean) life expectancy amongst males in coun

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Math Expert
Joined: 02 Sep 2009
Posts: 58453
If the average (arithmetic mean) life expectancy amongst males in coun  [#permalink]

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07 Jan 2018, 23:04
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25% (medium)

Question Stats:

84% (01:15) correct 16% (01:22) wrong based on 31 sessions

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If the average (arithmetic mean) life expectancy amongst males in country X is 68 years while the life expectancy of females is 72 years, what is the average life expectancy for the entire population?

(1) The ratio of males to females is 14 : 17.
(2) The number of females exceeds the number of males by one million.

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Re: If the average (arithmetic mean) life expectancy amongst males in coun  [#permalink]

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10 Jan 2018, 23:09
Bunuel wrote:
If the average (arithmetic mean) life expectancy amongst males in country X is 68 years while the life expectancy of females is 72 years, what is the average life expectancy for the entire population?

(1) The ratio of males to females is 14 : 17.
(2) The number of females exceeds the number of males by one million.

Lets say number of males in country X = M and number of females in country X = F. So total life of males = 68*M, and total life of females = 72*F. Average life expectancy = (Total life)/(total number of people) = (68M + 72F)/(M+F)

(1) Ratio of males to females = M:F = 14:17. We can put M=14k and F=17k in the formula to get the answer.
Average life expectancy = (68*14k + 72*17k)/(14k + 17k). 'k' will be eliminated and we will get the answer. Sufficient.

(2) F = M + 1000000.
Average life expectancy = [68M + 72(M+100000)]/[M+M+1000000]. This cannot be determined until we know the value of M. So Insufficient.

Re: If the average (arithmetic mean) life expectancy amongst males in coun   [#permalink] 10 Jan 2018, 23:09
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