swerve wrote:In Dewey Elementary School, there are two second-grade classes: class A has 35 students and class B has 45 students. If 40% of the students in class A walk to school, and 80% of the students in class B walk to school, what percent of all the students in the second-grade at Dewey Elementary walk to school?
A. 40%
B. 42.5%
C. 60%
D. 62.5%
E. 75%
Student ratio for A to B = 35:45 = 7:9.
Of every 16 students, 7 are in A and 9 are in B.
Since the walk rate for A is 40%, while the walk rate for B is 80%, the average walk rate per 16 students is as follows:
(7*40 + 9*80)/16 = 1000/16 = 500/8 = a bit more than 60.
The correct answer is
D.
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