A survey of 400 non-fatal accidents showed that 189 involved the use of a cell phone. Find a point estimate for p, the population proportion of non-fatal accidents that involved the use of a cell phone. Find the 95% confidence interval for the proportion of non-fatal accidents that involved the use of a cell phone

The point estimate for the proportion is p = 0.4725

The 95% confidence interval for the proportion of non-fatal accidents that involved the use of a cell phone is (0.4236, 0.5214).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.

In which

z is the zscore that has a pvalue of .

For this problem, we have that:

Point estimate

95% confidence level

So , z is the value of Z that has a pvalue of , so .

The lower limit of this interval is:

The upper limit of this interval is:

The 95% confidence interval for the proportion of non-fatal accidents that involved the use of a cell phone is (0.4236, 0.5214).