数学题：某班在植树活动中，平均每人植树7.5棵，若男女分开计算，则男生平均植树9棵，女生平均植树5棵，该班男生占全班人数的（ ）%。怎么写？

数学题解答：此题可用设数法，结合方程来解决。

把全班人数看作“1”，男生设为x。则有

[9x + (1-x)×5]÷1=7.5

4x+5=7.5

x=0.625

男生占总人数的：0.625÷1＝62.5%

答：该班男生占全班人数的（ 62.5）%。

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