In a class of 80 seniors, there are 3 boys for 5 every girls. In the junior class, there are 3 boys for every 2 girls. If the two classes combined have an equal number of boys and girls, how many students are in the junior class?

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Answer 1 · 2016-02-13T16:10:44

Number of students in junior class= 100

In the class of seniors there would be #80*3/8#= 30 boys and therefore 50 girls.

Now suppose there are x number of boys and girls in the junior class. The number of boys would be #(3x)/5# and number of girls would be #(2x)/5#

If two classes are combined then total number of boys would be #30+(3x)/5# and girls would be #50+ (2x)/5#

Since the number of boys and girls are now equal,
#30+(3x)/5 = 50 +(2x)/5#

#(3x)/5 -(2x)/5= 50-30#

#x/5 = 20#

x= 100