Question
What is the average of first 30 multiples of
9?Solution
ATQ- 9,18,27,........270. n=30, a=9 ,d=9 total of numbers =n/2(2a+(n-1).d =30/2(2×9+(30-1).9 =15(18+29×9) =15(18+261) =15×279 Average =(15×279)/30 =279/2 =139.5
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