1. the quality control manager at a light-bulb factory needs to estimate the mean life of a new type of light-bulb. the population standard deviation is assumed to be 60 hours. a random sample of 32 light-bulbs shows a sample mean life of 490 hours. construct and explain a 95% confidence interval estimate of the population mean life of the new light-bulb.

The 95% confidence interval estimate of the population mean life of the new light-bulb is (469.21 hours, 510.79 hours).

This confidence level means that we are 95% sure that the true population mean life of the new light bulb is in this interval.

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now we find M as such:

In which is the standard deviation of the population and n is the length of the sample. So:

The lower end of the interval is the mean subtracted by M. So it is 490 - 20.79 = 469.21 hours.

The upper end of the interval is the mean added to M. So it is 490 + 20.79 = 510.79 hours.

The 95% confidence interval estimate of the population mean life of the new light-bulb is (469.21 hours, 510.79 hours).

This confidence level means that we are 95% sure that the true population mean life of the new light bulb is in this interval.

the equation cos(35) =a/25 can be used to find the length of bc what is the length of bc? round to the nearest tenth

step-by-step explanation:

step-by-step explanation: it is d