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The average score of boys in an examination of a school is 71 and that of the girls is 73ăThe average score of the schoolis 71.8. Find the ratio of the aumber of boys to the number of girls that appeared in the examination. |
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Answer» Let the number of boys = xnumber of girls = ywe need to find= x/y The average score of boys in the examination is 71total score of boys = 71×x = 71xThe average score of girls in the examinationis 73total score of girls = 73× y = 73ySo total mark of school = 71x + 73y------(1) average score of school in examination 71.8so total mark = 71.8× (x+y) -----(2) From equations (1) and (2);71x + 73y = 71.8(x+y)⇒ 71x + 73y = 71.8x + 71.8y⇒ 73y - 71.8y = 71.8x - 71x⇒ 1.2y = 0.8x⇒ 0.8x = 1.2y⇒ x/y = 1.2/0.8 = 3/2 Ratio of boys and girls is 3:2. |
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