According to the Internal Revenue Service, income tax returns in a recent year averaged $911 in refunds for taxpayers. One explanation for this is that taxpayers would rather have the government keep back too much money during the year than owe it money at the end of the year. Suppose the average amount of tax at the end of a year is a refund of $911, with a standard deviation of $525. Assume that amounts owed or due on tax returns are normally distributed. What proportion of the tax returns show that the taxpayer owes money to the government? 

Historically, the Taco Bell nearest campus bags 85% of orders correctly. If a random sample of 100 orders is taken, is the sample size large enough to ensure that the sampling distribution of the sample proportion is normally distributed? 

Given the recent economic downturn, only 60% in a graduating class of 250 will find employment in the first round of a job search. You have 20 friends who have recently graduated. Assume that your friends represent a random sample.Calculate the standard error of the population proportion. 

According to the Internal Revenue Service, income tax returns in a recent year averaged $911 in refunds for taxpayers. One explanation for this is that taxpayers would rather have the government keep back too much money during the year than owe it money at the end of the year. Suppose the average amount of tax at the end of a year is a refund of $911, with a standard deviation of $525. Assume that amounts owed or due on tax returns are normally distributed. What proportion of tax returns show a refund of between $900 and $1,000?  

23% of registered voters in California are registered as “no party” or unaffiliated (Meaning not Democrat nor Republican).In a sample of 200 registered voters in California, what is the probability that more than 20% are unaffiliated? (4 decimal places) 

Which the null hypothesis is true for an ANOVA for comparing four treatment?

Simple linear regression: what is the predicted value of y when x has the value ?

In an ANOVA, we find that the p-value is 0.00001. We therefore conclude that:

Researchers wanted to investigate whether there was a relationship between marketing sales and advertising spending in the pharmaceutical industry. Which test do you recommend?

The relationship between number of glasses of wine consumed (x) and blood alcohol content (y) was studied in 500 adults by using least squares regression. The following regression equation shown below:                                                                                implies that