A randomly selected sample of 60 mathematics majors spent an average of 200.00 for textbooks one term, while during the same term, a randomly selected sample of 40 literature majors spent an average of 180.00 for textbooks. The standard deviation for each sample was 20.00 . The standard error for the difference between the two sample means is
a. 0.057
b. 4.082
c. 5.744
d. 16.663
Q. 2The number of first-year students who will decide to live in dormitories is a binomial random variable X with n = 1000 and p = 0.50 . Use the normal approximation with continuity correction to approximate the probability that X will be no more than 490, P(X 490).
a. 0.2743
b. 0.2709
c. 0.7291
d. 0.7357
Q. 3A random sample of 250 third graders scored an average of 3.2 on a standardized reading test. The standard deviation was 0.95 . What is the standard error of the sample mean?
a. 0.95
b. 0.202
c. 0.0038
d. 0.060
Q. 4The average time taken to complete an exam, X, follows a normal probability distribution with mean = 60 minutes and standard deviation 30 minutes. By what time should 99 of the students have finished the exam? (i.e. What is the 99th percentile for X?)
a. 85.2 minutes
b. 89.4 minutes
c. 129.9 minutes
d. 150.0 minutes
Q. 5A randomly selected sample of 30 students spent an average amount of 40.00 on a date, with a standard deviation of 5.00 . The standard error of the sample mean is
a. 0.063
b. 0.167
c. 0.913
d. 5.000
Q. 6The average time taken to complete an exam, X, follows a normal probability distribution with mean = 60 minutes and standard deviation 30 minutes. By what time should 67 of the students have finished the exam? (i.e. What is the 67th percentile for X?)
a. 60.0 minutes
b. 73.2 minutes
c. 77.9 minutes
d. 82.5 minutes
Q. 7A randomly selected sample of 100 students had an average grade point average (GPA) of 3.2 with a standard deviation of 0.2 . The standard error of the sample mean is
a. 0.020
b. 0.200
c. 1.600
d. 2.000
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