Chicken Delight claims that 90 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 100 orders revealed that 82 were delivered within the promised time. At the .10 significance level, can we conclude that less than 90 percent of the orders are delivered in less than 10 minutes?

Question

no idea when it come to statisitics how to use the formulas correctly

any help is greatly appreciated

Answer 1

Let's try a binomial proportion one-sample z-test for this problem. I'll give you the setup for the calculations and let you take it from there.

Formula with your data included:
z = (.82 - .9)/√[(.9)(.1)/100]
Note: .82 is 82/100; .9 is 90% from the problem; .1 is 1-.9; 100 is the sample size.

Finish the calculation. Check a z-table for .10 level of significance to determine your critical or cutoff value to reject the null or fail to reject the null hypothesis. You can then draw your conclusions.

I hope this will help get you started.