J.D. Power and Associates says that 50 percent of car buyers now use the Interne
ID: 3050184 • Letter: J
Question
J.D. Power and Associates says that 50 percent of car buyers now use the Internet for research and price comparisons.
Find the probability that in a sample of 10 car buyers, all 10 will use the Internet. (Round your answer to 4 decimal places.)
Find the probability that in a sample of 10 car buyers, at least 7 will use the Internet. (Round your answer to 4 decimal places.)
Find the probability that in a sample of 10 car buyers, more than 6 will use the Internet. (Round your answer to 4 decimal places.)
Find the mean and standard deviation of the probability distribution. (Round your mean value to 2 decimal places and standard deviation to 4 decimal places.)
J.D. Power and Associates says that 50 percent of car buyers now use the Internet for research and price comparisons.
Explanation / Answer
P(X=x) = nCx p^x q^(n-x)
p= 0.5
a)
n= 10
P(X=10)=
10C10 * 0.5^10 * 0.5^(0)
=BINOM.DIST(10,10,0.5,FALSE)
0.0010
b)
n= 10
P(X>=7)
1-p(x<=6)
=1-BINOM.DIST(6,10,0.5,TRUE)
0.1719
c)
n= 10
P(X>6) =
1-P(X<=5)
=1-BINOM.DIST(5,10,0.5,TRUE)
0.3770
d)
mean = np =0.5*10 = 5.00
var= npq= =10*0.5*(1-0.5) = 2.5
sd=sqrt(var)= =SQRT(2.5) = 1.5811
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