Question

What is the sum of this geometric series?

Answer 1

• B. 21/2

Explanation:

According to sigma notation we have a GP with:

• The first term of 8
• The common ratio of 1/4

Find the sum of the first 3 terms:

• Sₙ = a₁(1 - rⁿ) / (1 - r)
• S₃ = 8*(1 - 1/4³) / (1 - 1/4) = 8*(1 - 1/64) / (3/4) = 8*63/64 * 4/3 = 21 / 2

Correct choice is B