It has been reported that 39% of college students graduate in 4 yrs. Consider a random sample of 30 students and let the random variable X be the number who graduate in 4 years.
a. find the probability that 13 students in the sample of 30 graduate in 4 yrs?
b. Find the Probability that 15 or fewer students in the sample graduate in 4 yrs?
c. Using the results in part b, calculate by hand the probability that more than 15 students in the sample graduate in 4 yrs.
I just need to be at least started off because my professor hasn't explained this and expects it to be done tomorrow and the book is a vast pit of nothingness.
I can't do the stats question below.. help?
a. Formula is nCr p^r q^(n-r) where n = total number of trials, r = number of successes, p = probability of success and q = 1-p = prob. of failure.
So 30 C 13 (.39)^13 (.61)^17 = 0.13 (about)
15 or fewer requires either solving for 15, 14, 13, 12,...,1,0 and adding them up, using a binomial distribution chart, or a calculator such as a TI-84, which says the answer is 0.92
More than 15 by hand is just 1 - 0.92 = 0.08 since it's all that's left over from b
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment