这道题的确实有问题。“The ratio of the number of boys in primary 5A to the number of boys in primary 5B was 3:4”或“The ratio of the number of girls inprimary 5A to the number of girls in primary 5B,was 4:3"这两个条件拿掉任何一个这道题都能成立,放在一起就不行了。
有两种做法, 两个不同的答案。
方法1
Total units of boys --> 3+4=7 Each units --> 56/7=8 Nos of boys in 5A --> 8x3 =24 Nos of boys in 5B --> 8x4 =32 Nos of girls in 5B --> 42-32=10 Nos of girls in 5A --> 42-24 =18
Ratio of boys in 5A to girls in primary 5B --> 24:10 = 12:5
方法2Nos of girls --> 42x2-56 =28 Total units of girls --> 28/(4+3)=4 Nos of girls in 5A --> 4x3 =12 Nos of girls in 5B --> 4x4 =16 Nos of boys in 5A --> 42-12=30 Nos of boys in 5B --> 42-16=26
Ratio of boys in 5A to girls in primary 5B -->30:16=15:8
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