Question

Find the sum of the geometric series in which a1=160, a6= 5 and r= ½

Answer 1

Answer:

Sn = 315

The sum of the first six terms of the series is 315

Completed question:

Find the sum of the first six terms of the geometric series in which a1=160, a6= 5 and r= ½

Step-by-step explanation:

The sum of a geometric series in with common ratio

r < 1 is;

Sn = a(1 - r^n)/(1-r)

Where;

r = common ratio

a = first term

n = nth term

Given;

r = 1/2

a = a1 = 160

n = 6

Substituting the values, we have;

Sn = 160(1 - (1/2)^6)/(1 - 1/2)

Sn = 315

The sum of the first six terms of the series is 315