If 25 students in one class

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If 25 students in one class

by farukqmul » Wed Jun 27, 2012 7:15 am
]If 25 students in one class had an average of 93 % and 20 students from another class had an average of 98 %,approximately what is the average in percent of all 45 students ?
A. 94 B. 97 C. 95.5 D. 95.2 E. 93
Can anyone tell me how to do this math in a shortest way ?Thanks

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by Anurag@Gurome » Wed Jun 27, 2012 7:23 am
farukqmul wrote:]If 25 students in one class had an average of 93 % and 20 students from another class had an average of 98 %,approximately what is the average in percent of all 45 students?
Average of all = (25*93 + 20*98)/45 = (5*93 + 4*98)/9 = [5*(100 - 7) + 4*(100 - 2)]/9 = [500 - 35 + 400 - 8]/9 = [900 - 43]/9 = (100 - 43/9) ≈ (100 - 4.8) ≈ 95.2

The correct answer is D.
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