Question

Find the sum of the first 150 terms of the arithmetic series: 4, 5, 6, 7, 8, … 7,345 11,775 13,322 15,654

Answer 1

4, 5, 6, 7, 8, . . .
a = 4, d = 5 - 4 = 1, n = 150
Sn = n/2[2a + (n - 1)d]
S(150) = 150/2[2(4) + (150 - 1)1] = 75[8 + 149] = 75(157) = 11,775