
Peter A. answered 09/28/21
Statistics Econometrics Finance tutor with 10 years experience
(a)
By the compliment rule,
P(failure)=1-0.15=0.85
P(r=0)=P(8 failures)
By the multiplicative rule for independent events (Binomial events are independent)
P(8 failures)=0.85^8=0.272
Hence P(r=0)=0.272
(b)
By the compliment rule,
P(r>=1)=1-P(r=0)=1-0.272=0.728