math 3339 final Questions and Answers100% Correct
A distribution of grades in an introductory statistics class (where A = 4, B = 3, etc) is:
x= 0,1,2,3,4
p(x)= 0.1,0.18,.22,.31,.19
find the mean and variance correct answer sum(x*p)
sum(x^2*p)-(sum(x*p)^2)
A potato chip company calculated that there is a mean of 75.4 broken potato chips in each production
run with a standard deviation of 5.2. If the distribution is approximately normal, find the probability that
there will be fewer than 66 broken chips in a run. correct answer pnorm(66,75.4,5.2)
A private and a public university are located in the same city. For the private university, 1046 alumni
were
surveyed and 653 said that they attended at least one class reunion. For the public university, 791 out of
1327
sampled alumni claimed they have attended at least one class reunion. Is the difference in the sample
proportions statistically significant? correct answer two sample z test
A random sample of 121 cans of fruit nectar is drawn from among all cans produced in a run. Prior
experience has shown that the distribution of the contents has a mean of 12.13 ounces and a standard
deviation of 2.14 ounce. What is the probability that the average contents of the 121 sample cans is less
than 11.81 ounces? correct answer pnorm(11.81,12.13,2.14/sqrt(121))
A random sample of 144 observations produced a sample proportion of 0.35. An approximate 90%
confidence interval for the population proportion p is between correct answer 0.35+c(-
1,1)*qnorm(1.9/2)*sqrt(0.35*(1-0.35)/144)
A random variable X has a probability distribution as follows:
X = 01234
P(X)= 7k 4k 2k 4k 4k
Find P(x<2) correct answer 7k+4k+2k+4k+4k=21k
A distribution of grades in an introductory statistics class (where A = 4, B = 3, etc) is:
x= 0,1,2,3,4
p(x)= 0.1,0.18,.22,.31,.19
find the mean and variance correct answer sum(x*p)
sum(x^2*p)-(sum(x*p)^2)
A potato chip company calculated that there is a mean of 75.4 broken potato chips in each production
run with a standard deviation of 5.2. If the distribution is approximately normal, find the probability that
there will be fewer than 66 broken chips in a run. correct answer pnorm(66,75.4,5.2)
A private and a public university are located in the same city. For the private university, 1046 alumni
were
surveyed and 653 said that they attended at least one class reunion. For the public university, 791 out of
1327
sampled alumni claimed they have attended at least one class reunion. Is the difference in the sample
proportions statistically significant? correct answer two sample z test
A random sample of 121 cans of fruit nectar is drawn from among all cans produced in a run. Prior
experience has shown that the distribution of the contents has a mean of 12.13 ounces and a standard
deviation of 2.14 ounce. What is the probability that the average contents of the 121 sample cans is less
than 11.81 ounces? correct answer pnorm(11.81,12.13,2.14/sqrt(121))
A random sample of 144 observations produced a sample proportion of 0.35. An approximate 90%
confidence interval for the population proportion p is between correct answer 0.35+c(-
1,1)*qnorm(1.9/2)*sqrt(0.35*(1-0.35)/144)
A random variable X has a probability distribution as follows:
X = 01234
P(X)= 7k 4k 2k 4k 4k
Find P(x<2) correct answer 7k+4k+2k+4k+4k=21k
