
A sample of 25 days in summer yields an average
high temperature of 80 with a standard deviation of 12.

Give a point estimate of the true mean of the
high temperature.

Find a 99% confidence interval for the average
high temperature for the summer.

How big a sample do we need if we want to be 90%
confident of being within 7 degrees of the population mean?

A sample of 100 exams yielded an average grade
of 82 and standard deviation of 14.Find
a 95% confidence interval for the average exam grade.

Heights of aliens from Mars are known to be
normally distributed with a population standard deviation of 9 inches.How big a sample do we need to take if we
want be 95% confident that our error will not exceed 3 inches?

Preliminary studies have shown that 20% of the
voters might be willing to vote for Sran for President.

Construct a 90% confidence interval for the
proportion of voters who would be willing to support Sran.

Before entering the race, Sran would like to conduct
a poll to check his level of support.How
big should be the sample be if he wants to be 95% sure that the error is no
more than 2%?

The average weight of men joining a gym has
historically been 170 pounds with a standard deviation of 27.The owner feels that the average weight has
now decreased to less than 165 pounds.
To support his claim, the owner conducts a sample of 25 men and finds
their average to be 153.He would like
to use a significance level of .05 to test his claim.

State the null hypothesis.

State the alternate hypothesis.

Will you use z or t distribution for this
problem?

Is this a twotail test or a onetail test?Draw a normal curve representing the problem.

Determine the critical value.

Determine the rejection region.

Calculate the test statistic.

Would you accept or reject the owner’s
claim?Explain.

The average score on a certain college entrance
test has been known to be 240.The dean
of a university feels that this has changed.
He conducts a sample of 25 students to test his claim.The sample yields an average of 232 with a
standard deviation of 25. He would like to use a significance level of .10.

State the null hypothesis.

State the alternate hypothesis.

Will you use z or t distribution for this
problem?

Is this a twotail test or a onetail test?Draw a normal curve representing the problem.

Determine the critical value.

Determine the rejection region.

Calculate the test statistic.

Would you accept or reject the dean’s claim?

A presidential candidate states that she
currently has exactly 30% of the vote.A
newspaper thinks that this number is inaccurate.So it conducts a sample 500 voters and finds 175
people support the candidate.The
newspaper would like to test its claim using .05 significance level.

State the null hypothesis.

State the alternate hypothesis.

Will you use z or t distribution for this
problem?

Is this a twotail test or a onetail test?Draw a normal curve representing the problem.

Determine the critical value.

Determine the rejection region.

Calculate the test statistic.

Would you accept or reject the newspaper’s
claim?