SSC MTS 5 Aug 2019 Shift 1 Paper

As we know,
Sum first n natural numbers = [n (n + 1)]/2
Sum of first 48 numbers = (48 × 49)/2 = 1176
Sum of first 125 numbers = [125 × 126]/2 = 7875
Sum of natural numbers from 49 to 125 = 7875 – 1176 = 6699
Total number from 49 to 125 = 125 – 48 = 77
Average of all the natural numbers from 49 to 125 = 6699/77 = 87