An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 45 hours. if a sample of 35 bulbs has an average life of 710 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm.

[693,38:725,62]hs

Step-by-step explanation:

Hello!

Your study variable is X: the lifespan of a light bulb. This variable is said to have an approximately normal distribution.

X≈N(μ;σ²)

Were

μ= populatiom mean

σ= 45 hs standard deviation

A sample of n= 35

To estimate the population mean with a confidence interval you have to use the Z statistic:

X{bar} ± *(σ/√n)

710 ± 2.054*(45/√35

[693,38:725,62]hs

I hope you have a SUPER day!

the correct answer is the second option

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.