In: Statistics and Probability
Suppose that Apple Inc. wished to estimate the mean time people spend on their phones every day. In a random sample of 30 phones users the mean time was found to be 150 minutes with a standard deviation of 70 minutes.
* Construct a 90% confidence interval for the mean time people spend on their phone every day.
* Construct a 95% confidence interval for the mean time people spend on their phone every day.
* Construct a 99% confidence interval for the mean time people spend on their phone every day.
*As you increased the level of confidence what happens to the the width of your confidence intervals?