Question

1. One light bulb is selected at random from a lot of 120 light bulbs of which 5% are defective. What is the probability that the selected light bulb is defective?

a. 0.05

b. 0.2

c. 0.1667

d. 0.06

Answer 1

The correct answer is a. The probability is 0.05. We can use it straight away or we can compute the number of defective bulbs: $n=120\cdot0.05=6$ and then compute the probability using formula: $p=\frac{6}{120}=0.05$