A recent survey found that 70% of all adults over 50 wear glasses for driving. In a random sample of 10 adults over 50, what is the probability that at least six wear glasses?
2007-03-08 03:06:47 · 2 answers · asked by Student12345 2 in Science & Mathematics ➔ Mathematics
This is a binomial. The number of trials, n, is 10. There is either a success (wear glasses) or failure (not wear glasses) on each trial, the probability of success, p, is 0.7 for each trial, and the trials are independent.
P(At least 6) = P(6)+P(7)+P(8)+P(9)+P(10)
= 10!/6!4!(0.7^6)(0.3^4) + 10!/7!3!(0.7^7)(0.3^3) + 10!/8!2!(0.7^8)(0.3^2) + 10!/9!1!(0.7^9)(0.3^1) + 10!/10!0!(0.7^10)(0.3^0)
= 0.2001 + 0.2668 + 0.2335 + 0.1211 + 0.0282
= 0.8497
BTW the answer is not 70%. That is the percentage on each trial.
2007-03-08 03:20:36 · answer #1 · answered by blahb31 6 · 1⤊ 0⤋
Probability of over
50 wearing glasses=0.7=7/10
Ans=7/10
or
70%of 10=7/10
2007-03-08 11:11:42 · answer #2 · answered by Maths Rocks 4 · 0⤊ 1⤋