Originally Posted by

**Jonas8000** Hi

Hope you can help me with my problem. Hope you understand my English :)

A phone company asks 50 people about their waiting time, when they call the customer service.

The sample mean is 8.4 minutes and the standard deviation is 7.8 min.

We also know that 10 out of the 50 people are waiting for longer than 15 min.

So I know that ´x = 8.4 and s = 7.8.

Question 1:

Determine the 95% confidence interval estimate of the mean waiting time

I solve this question with the t interval formula.

But I am lost at the next question

*Question 2:*

*I am supposed to make a hypotheses test for the proportion. Can the company clam that under ¼ of the customers are waiting for UNDER 15min??*

I am lost??

How can I do that?? Well I am not quite sure how to define Ho and H1?

Hope you can help me :)

And thank you all for sharing your knowledge! :)