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 By: cheemengszl (offline)  Saturday, May 19 2012 @ 10:14 PM CDT (Read 915 times)
cheemengszl

In a school bus,there were 2/5 as many boys as girls.After 3 boys alighted from the bus and another 3 girls boarded the bus, there aere now 1/3 as many boys as girls in the bus.How many students were there in the bus at first?

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 By: awyw1201 (offline)  Saturday, May 19 2012 @ 11:02 PM CDT
awyw1201

Quote by: cheemengszl

In a school bus,there were 2/5 as many boys as girls.After 3 boys alighted from the bus and another 3 girls boarded the bus, there aere now 1/3 as many boys as girls in the bus.How many students were there in the bus at first?

Because 3 boys alighted and 3 girls boarded, the total number of children before and after remains unchanged.

Use ratio

B4-------B:G=2:5

After----B:G=1:3

The total B4=2+5=7 and the total after 1+3 =4

L.C.M of 7 and 4 is 28.

So,

B4-------B:G=2x4:5x4 = 8:20

After----B:G=1x7:3x7 = 7:21

8-7 = 1u-----3
20+8=28u---28x3 = 84

Ans: 84 students

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Registered: 07/08/11
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