Question

sum of first 50 multiples of three

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Answer 1

Answer:

Now the highest multiple of 3 less than 50 is 48 (hope you get it).

Now we have to calculate the sum of 3 + 6+……+48

Now we will first calculate number of terms on this A.P.

Now we know that

Last term = first term +(number of terms -1) * common difference

=> 48 = 3 + (n-1)*3

=> 45=(n-1)*3

=> 45/3 = n-1

=> 15 = n-1 => n= 16

Now sum in A.P. is calculated as

Sum = (number of terms/2)*(first term + last term)

=> Sum = (16/2)*(3 +48)

=> Sum = 8*51= 408

So the sum of all positive multiple of 3 less than 50 is 408 .

Hope it helps !!! Have a good day !