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3 years, 9 months ago
3 years, 9 months ago
Hint -> add serial number to every number
like 24+1 , 45+2,a+3,....74+10 -> 395+(1+2...10)+a+b
Sum of First N natural numbers n(n+1)/2
sum of First 10 Natural Numbers 10(11)/2 = 55
Now avg =( 395+55+a+b)/10 = 55
a+b = 100
average of a and b is 100/2 = 50
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