In: Statistics and Probability
BINOMIAL PROBABILITIES Big Box Store (BBS) has an annual rate of 4% of all sales being returned. In a recent sample of thirty randomly selected sales the number of returns was five. BBS is concerned about the event, and your advice is solicited. FOR 4 – 9, OPEN THE EXCEL EXAM TWO FILE. THE SPREADSHEET FOR THIS PROBLEM IS FOUND ON SHEET TWO. COMPLETE AND SAVE YOUR WORK IN EXCEL AND ENTER THE SOLUTIONS BELOW. (6) (2.5points) What is the probability that a random sample of 30 sales has 5 or fewer returns? Type the answer and any work below.
6) p = 0.04 …Probability of a sale being
returned (4%)
n = 30 …sample of 30 sales
Let X be the number of sales returned in the sample of
30
Then X ~ Binomial(n = 30, p = 0.04)
To find P(random sample of 30 sales has 5 or fewer
returns)
that is to find P(X ≤ 5)
We use Excel function BINOM.DIST to find the
probability
P(X ≤ 5) = BINOM.DIST(5, 30, 0.04, TRUE)
= 0.9989
P(random sample of 30 sales has 5 or fewer
returns) =