Finite probability

Question

1. A coin is weighted so that the probability of obtaining a head in a single toss is 0.6. If the coin is tossed 30 times, find the following probabilities. (Round your answers to four decimal places.)

(a) fewer than 17 heads

 

(b) between 17 and 21 heads, inclusive

 

2.The manager of Madison Finance Company has estimated that, because of a recession year, 6% of its 400 loan accounts will be delinquent. If the manager's estimate is correct, what is the probability that 27 or more of the accounts will be delinquent? (Round your answer to four decimal places.)

(c) more than 23 heads

Answer 1

a) mean = np = 30(.6) = 18 var = npq = 18(.4) = 7.2

sd = sqr7.2 = about 2.68328

z = (17-18)/(sqr7.2) = about .3727

P(x</=17) = about 35.47%

use z tables