Lindsey S.

asked • 08/20/18

there was a total of 280 students in class , the ratio was 3:8 beginning year and 4:7 end of year how many more signed up

there was a total of 280 students in class , the ratio was 3:8 beginning year and 4:7 end of year how many more signed up

Larry C.

Insufficient information:
a) Is 280 the number of students at the beginning or the year or end of the year?
b) Are the ratios male/female, female/male or something else altogether? In any case, we'd have to also know the size of at least one of the subgroups to make any attempt at a solution.
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08/21/18

1 Expert Answer

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Raymond B. answered • 11/26/20

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3:8 with 280 means 3/11 to 8/11 of 280 or 840/11:2240/11


to change to 4:7 means either more of the 1st group signed up or less of the 2nd group dropped out, or some combination. but assume no one dropped out, then more of the 1st group signed up


let that number be x


840/11 + x = (840+11x)/11 to 2240/11 is 4:7


840+11x over 2240 = 4/7

5880 + 77x = 8960

77x = 8960-5880 = 3080

x = 3080/77= 40 new students enrolled



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