### [solution] » A firm produces batteries that have a lifetime which is normally distributed with a mean of 355 m

Description

The Question

A firm produces batteries that have a lifetime which is normally distributed with a mean of 355 minutes and a standard deviation of 14 minutes. The firm needs to keep an eye on the production process to ensure that everything is working properly and that batteries are not being produced that do not meet the advertised standard. This is done by calculating the mean of the sample. To do this they regularly select a sample of 49 batteries in order to test the process.

(a)Describe the sampling distribution of the sample mean lifetime of batteries

(b)State a range within which you would expect the middle 80% of the sample means to lie.

(c)If the process were working correctly, what is the probability that a sample would produce a mean of less than 350 minutes?

(d)Based on your answer to part (c), what would you conclude about the process if the sample produced a mean life of batteries of 350 minutes?

(e)What is the probability that two samples in a row would have a mean life time of less than 350 minutes (Hint: as the two samples are independent, so please refer to the joint probability for independent events.)?

#### Solution details

Solution #00070333

##### [solution] » A firm produces batteries that have a lifetime which is normally distributed with a mean of 355 m.zip

This paper was answered on 14-Oct-2020

STATUS

QUALITY

Approved

Oct 14, 2020

EXPERT

Tutor

#### BEST TUTORS

We have top-notch tutors who can do your essay/homework for you at a reasonable cost and then you can simply use that essay as a template to build your own arguments.

You can also use these solutions:

• As a reference for in-depth understanding of the subject.
• As a source of ideas / reasoning for your own research (if properly referenced)
• For editing and paraphrasing (check your institution's definition of plagiarism and recommended paraphrase).
This we believe is a better way of understanding a problem and makes use of the efficiency of time of the student.