It is reported that 77% of workers aged 16 and over drive to work alone. Choose 8 workers at random. Find the probability that at most 7 drive at work alone

Answer 1

x = number that drive to work alone

The probability that at most 7 drive to work alone is equal to 1 - probability that exactly eight drive to work alone

P(x <= 7) = 1 - P(x > 7) = 1- P(x = 8)

That probability can be found using the binomial formula:

Probability 8 drive to work alone = C(8,8) 0.77^8 * 0.23^0 = 0.77^8 = 0.1236

1 - 0.1236 = 0.8764