help's answer to Louise's Primary 6 Maths Percentage Singapore question.
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so right at first theres 30 ppl in the band , 60% being boys, so u can find n.o of boys at first which is 60/100 x 30 = 18, and hence the rest are n.o of girls (note that no girls left the band) which is 30-18 = 12 girls
at first boy percentage is 60%, girls 40%
but when some left its now 20% boys, 80% girls.
Since we know the n.o of girls (which didn't change), this means that 80/100 of the band in the end are girls, which is 12 girls (80/100 =12) we can use that to find total n.o of ppl in the band which is 100/80 x 12 = 15 ppl , which means that theres only 15 ppl left,
hence the n.o of boys who left = 30(at first) - 15(in the end) = 15 boys who left the band (only applies if the n.o of girls did not change)
at first boy percentage is 60%, girls 40%
but when some left its now 20% boys, 80% girls.
Since we know the n.o of girls (which didn't change), this means that 80/100 of the band in the end are girls, which is 12 girls (80/100 =12) we can use that to find total n.o of ppl in the band which is 100/80 x 12 = 15 ppl , which means that theres only 15 ppl left,
hence the n.o of boys who left = 30(at first) - 15(in the end) = 15 boys who left the band (only applies if the n.o of girls did not change)
Date Posted:
3 years ago
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