anuptvm wrote:Linda's grade was 90th percentile of 80 grades for her class. Of the 100 grades from another class, 19 were higher than Linda's, and the rest lower. If no other grade was the same as Linda's grade, then Linda's grade was what percentile of the grades of the two classes combined?
1. 72nd 2. 80th 3. 82nd 4. 85th 5. 92nd
OA is 4
Could someone explain this. I tried using the weighted average method but was wrong.
Percentile means the percentage below.
Out of 80 grades, if Linda's grade was the 90th percentile, then 90% of the grades were lower than Linda's grade. Thus, .9*80 = 72 grades in Linda's class were lower than Linda's grade. Subtracting these 72 grades and Linda's grade from the total, we get that 80-72-1 = 7 grades were higher.
Since 19 grades in the other class were higher than Linda's grade, 19+7 = 26 grades in the combined classes were higher than Linda's grade. Subtracting these 26 grades and Linda's grade from the total number of grades in the combined classes, we get that 180-26-1 = 153 grades were lower than Linda's grade.
Thus, Linda's percentile in the combined classes was 153/180*100 = 85%.
The correct answer is
D.
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