In 2007,there are 1200 boys and girls in secondary school.In 2008,the number of students remained unchanged,but the number of girls was increase by 20% to 480 in comparing to that on 2007.
a)Find the number of boys and girls in 2007 respectively.
b)Find the percentage decrease in the number of boys in 2008.
s1 math per cent,equation 難題!!
2011-12-31 6:46 am
回答 (2)
2011-12-31 9:09 am
✔ 最佳答案
number of girl in 2007=480/(1+20%)
=480/120%
=480*(100/120)
=4*100
=400
number of boy in 2007
=1200-400
=800
percentage decrease
=(800-(1200-480))/1200*100%
=(800-720)/1200*100%
=80/1200*100%
=6/2/3%
參考: ME
2011-12-31 6:57 am
a.
No. of girls in 2007
= 480/(1+20%)
= 480/1.2
= 400
No. of boys in 2007
= 1200 - 400
= 800
b.
Percentage decrease in the number of boys in 2008
= 800/1200 * 100% - 800/(1200+480) * 100%
= 19.05%
No. of girls in 2007
= 480/(1+20%)
= 480/1.2
= 400
No. of boys in 2007
= 1200 - 400
= 800
b.
Percentage decrease in the number of boys in 2008
= 800/1200 * 100% - 800/(1200+480) * 100%
= 19.05%
參考: Hope the solution can help you^^”
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