The January 1986 mission of the Space Shuttle Challenger was the 25th such shuttle mission. It was unsuccessful due to an explosion caused by an O-ring seal failure.

(a) According to NASA, the probability of such a failure in a single mission was 1/60,827. Using this value of p and assuming all missions are independent, calculate the probability of no mission failures in 20 attempts. Then calculate the probability of at least one mission failure in 20 attempts. (Do not round your intermediate calculation and round your finalanswers to 4 decimal places.)

P(x=0)

P(x greater than or equal to 1)

(b) According to a study conducted for the Air Force, the probability of such a failure in a single mission was 1/35. Recalculate the probability of no mission failures in 20 attempts and the probability of at least one mission failure in 20 attempts. (Do not round your intermediate calculation and round your finalanswers to 4 decimal places.)

P(x=0)

P(x greater than or equal to 1)

(c)Based on your answers to parts a and b, which value of p seems more likely to be true?

1/35

1/36

1/60,827

(d) How small must p be made in order to ensure that the probability of no mission failures in 20 attempts is .999? (Round your answers to 5 decimal places.)

q

p