Question

Sum of numbers between 50&80

Answer 1

Let the nos from 50 to 80 be in AP.

Then,

50 + 51 +.............. +80. = AP

Now, a = 50, d= 1, l = 89

Total no of terms be n.

Then nth term = a + (n-1)d

80 = 50 + (n-1) ☓ 1

30 = n-1

n = 31.

So,

Sum of AP = n/2 (a +l)

Sum = 31/2 ☓ (50 +80)

Sum = 31/2 ☓ 130

Sum = 31 ☓ 65

Sum = 2015.

Hope this helps you......