A survey of several 10 to 11 year olds recorded the following amounts spent on a trip to the mall: $17.33,$19.83,$21.10,$24.20,$13.72,$17.82  Construct the 95% confidence interval for the average amount spent by 10 to 11 year olds on a trip to the mall. Assume the population is approximately normal. Step 3 of 4 :  Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. We are interested in determining if the accident proportions differ between the two age groups. The results are shown below. a =0.05 Under age of 18 Over age of 18 n₂ =500 n₁ = 480 Number of accidents = 160 Number of accidents = 140 The test statistic is A 90% confidence interval for the proportion between two age groups is approximately Given a 5% level of significance, what decision should be reached about the null hypothesis

In a survey, 22 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $38 and standard deviation of $4. Construct a confidence interval at a 90% confidence level.

In a survey, 24 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $36 and standard deviation of $15. Construct a confidence interval at a 90% confidence level.

In a survey, 19 people were asked how much they spent on their child's lost birthday gift. The results were roughly bellshaped with a mean of $46 and standard deviation of $8. Construct a confidence Interval at a 99% confidence level Give your answers to one decimal place:

A survey of 240 teachers found that two-thirds of those surveyed do not live in Sydney. Can you conclude statistically that the population proportion who do not live in Sydney is less than ​0.75? Use a​ 95% confidence interval. What is the confidence interval and is 0.75 within the interval?

I sampled 10 downtown Chicago restaurants for the price of their most expensive meal on the menu. Here are the prices: $45, $80, $70, $70, $60, $65, $80, $60, $50, $90 Construct a 99% confidence interval for the mean price of the most expensive meal at a downtown Chicago restaurant. Assume the population is approximately normal. Write a sentence using that confidence interval   Using the values in the previous question, compute a 95% confidence interval for the standard deviation of the most expensive price for a mean in downtown Chicago.

Use R Studio to answer the following question:

A 95% confidence interval for a population proportion, p, is 0.23 < p < 0.27. What was the sample proportion?

A learn-to-type software program claims that it can improve your typing skills. To test the claim and possibly help yourself out, you and six of your friends decide to try the program and see what happens. Use the table below to construct an 80% confidence interval for the true mean change in the typing speeds for people who have completed the typing program. Let Population 1 be the typing speed before taking the program and Population 2 be the typing speed after taking the program. Round the endpoints of the interval to one decimal place, if necessary. Typing Speeds (in Words per Minute) Before After 32 33 51 42 55 40 35 32 54 33 45 30 50 52