Question

The show 60 minutes recently had a share of 20, meaning that among the TV sets in use, 20% were tuned to 60
Minutes. An independent advertiser wants to check this statistic. They begin with 15 households having TV sets
and survey during the time 60 Minutes is on.
i. What is the probability that exactly 8 of the households are tuned to 60 Minutes.
A. 0.9966 B. 0.0035 C. 0.9992 D. 0.0138
ii. What is the probability that exactly 4 of the households is tuned to 60 Minutes?
A. 0.1876 B. 0.8124 C. 0.8358 D. 0.1642
iii. Find the mean, μ, of the binomial probability distribution: A. 2.4 B. 7.5 C. 3 D.

Answer 1

Use binomial distribution
P(x) = nCx*p^x*(1-p)^n-x
n = total num of households
x = households watching 60 min
p = probability household is watching 60 min based on recent ratings
Part 1:
n=15
x=8
p=0.2
P(8) = 15C8*(.2)^8*(.8)^7 = 0.0035
Part 2:
n=15
x=4
p=0.2
P(4) = 15C4*(.2)^4*(.8)^11 = 0.1876
Part 3:
mean = n*p
mean = 15*0.2 = 3

Hope this helps