Company hopes to improve customer satisfaction, setting a goal of no more than 5% negative comments. A random survey of 350 customers found only 14 with complaints. Does this provide evidence at the 10% significance level that the company has reached its goal of decreasing the percentage of complaints?

The company reported that two-thirds (67%) of adults with profiles on social sites have restricted access to their profiles by requiring passwords or making them available only to buddies on an approved  A researcher believes that law enforcement people are more aware with keeping themselves secure online and conducts a survey random sample of 100 enlisted police officers and finds that 78 police officers restrict access to their profiles. Does this indicate at the 5% significance level that a larger proportion of law enforcement protect their profiles on social sites?

The National Collegiate Athletic Association (NCAA) requires colleges to report the graduation rates of their athletes. Here are data from a Big 12 university's report. Ninety-five of the 147 athletes admitted in 1998-2001 graduated within six years. Does this indicate at a 1% significance level that the proportion of athletes who graduate differ significantly from the all-university proportion, which was 70%?

In a survey of 284 smokers, 197 smokers reported that they wanted to quit smoking. Compute a 90% confidence interval for the true proportion of smokers that want to quit smoking.

How to quit smoking.  Anti smoking pills  are often used to help smokers quit. Does giving medicine to fight anxiety help? A randomized double-blind experiment assigned 244 smokers who wanted to stop to receive nicotine patches and another 245 to receive both a patch and the antidepression drug bupropion. After a year, 40 participants in the nicotine patch group and 87 in the patch-plus-drug group had abstained from smoking

Is there a significantly higher proportion of the patients that receive the patch plus bupropion abstaining from smoking than the patch only group? Carry out a test of significance at the 5% significance level.

A random sample of individuals participated in a survey in 2000 were asked "Do you favor or oppose the death penalty for murder? The results were 130 out of 200 females favored capital punishment and 188 out of 250 males favored capital punishment. Find an approximate 95% confidence interval for the difference between the proportion of females and males that favor capital punishment.