InterviewSolution
Saved Bookmarks
| 1. |
Theaverage marks of boys in a class is 52 and that of girls is 42. The averagemarks of boys and girls combined is 50. The percentage of boys in the classis(1)40(2) 20(3) 80(4) 60A. 80B. 60C. 40D. 20 |
|
Answer» Correct Answer - A Let `n_(1) and n_(2)` be the number of boys and girls respectively in the class. We have, `bar(X_(1))=52,bar(X_(2))=42 and bar(X) =50` `therefore bar(X)=(n_(1)bar(X_(1))+n_(2)bar(X_(2)))/(n_(1)+n_(2))` `rArr 50=(52n_(1)+42n_(2))/(n_(1)+n_(2)) rArr 8n_(2)=2n_(1) rArr n_(1)=4n_(2)` `therefore " Percentage of boys "=(n_(1))/(n_(1)+n_(2)) xx 100=(4n_(2))/(5n_(2)) xx 100=80` |
|