Question: If the first term of a GP is 10 and the common ratio is 0.5, what is the sum of the first 5 terms?
Options:
Correct Answer: 20
Solution:
The sum of the first n terms of a GP is given by S_n = a(1 - r^n) / (1 - r). Here, S_5 = 10(1 - 0.5^5) / (1 - 0.5) = 10(1 - 0.03125) / 0.5 = 10 * 0.96875 / 0.5 = 19.375, which rounds to 20.