17. In a recent study, 820 American adults ware surveyed and 500 said they would travel less this year for nonbusiness trips than last year. Construct a 95% confidence interval for the true proportion of adults who said they would travel less this year for nonbusiness trips. Report your findings in an interpretive sentence. 18. The Humane Society would like to know what proportion of pets that people have, were adopted from a shelter. How large a sample should be selected in order to estimate this proportion with a 95% confidence level and a margin of error of at most 10%? (Assume no preliminary estimate of p-hat is available.) 19. A student records the repair costs for 20 randomly selected computers from a local repair shop where he works. A sample mean of $216.53 and standard deviation of $15.86 were calculated. Construct a 98% confidence interval to estimate the population mean repair cost for all computers repaired at the local shop. Then, report your findings in an interpretive sentence