Question

The life of a fully-charged cell phone battery is normally distributed with a mean of 14...

The life of a fully-charged cell phone battery is normally distributed with a mean of 14 hours with a standard deviation of 3 hours. What is the probability that 25 batteries last at least 13 hours?

Homework Answers

Answer #1

The probability that 25 batteries last at least 13 hours is

P(Xbar > 13) = P(Z > (13 - Mean) / (SD / sqrt(n))

              = P(Z > (13 - 14) / (3/sqrt(25))

= P(Z > -1.6667)

       = 1 - P(Z < -1.6667)

                    = 1 - 0.0478 = 0.9522

Therefore, The probability that 25 batteries last at least 13 hours is 0.9522

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
The life of a fully-charged cell phone battery is normally distributed with a mean of 14...
The life of a fully-charged cell phone battery is normally distributed with a mean of 14 hours with a standard deviation of 3 hours. What is the probability that 25 batteries last at least 13 hours?
The life of a fully-charged cell phone battery is normally distributed with a mean of 14...
The life of a fully-charged cell phone battery is normally distributed with a mean of 14 hours with a standard deviation of 3 hours. What is the probability that 25 batteries last less than 16 hours?
The life span of a battery is normally​ distributed, with a mean of 2400 hours and...
The life span of a battery is normally​ distributed, with a mean of 2400 hours and a standard deviation of 50 hours. What percent of batteries have a life span that is more than 2460 ​hours? Would it be unusual for a battery to have a life span that is more than 2460 ​hours? Explain your reasoning. What percent of batteries have a life span that is more than 2460 ​hours? Approximately_______% of batteries have a life span that is...
A battery manufacturer finds that the life of its batteries are normally distributed with a mean...
A battery manufacturer finds that the life of its batteries are normally distributed with a mean of 32 months and a standard deviation of 5 months. Find the probability that a battery lasts more than 36 months. Round off to four decimal places.
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a...
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of 85 hours and a standard deviation of 11 hours. Complete parts a through c. a. What is the probability that a single battery randomly selected from the population will have a life between 80 and 90​ hours? ​P(80≤ overbar x≤90​)= ​(Round to four decimal places as​ needed.) b. What is the probability that 4 randomly sampled batteries from the population will have...
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a...
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of 80 hours and a standard deviation of 11 hours. Complete parts a through c. a. What is the probability that a single battery randomly selected from the population will have a life between and hours? 75 85 P(75 ≤ x ≤ 85) = (Round to four decimal places as needed.) b. What is the probability that randomly sampled batteries from the population...
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a...
Suppose the life of a particular brand of calculator battery is approximately normally distributed with a mean of 75 hours and a standard deviation of 9 hours. Complete parts a through c. a. What is the probability that a single battery randomly selected from the population will have a life between 70 and 80 ​hours? ​P(70 < or = x overbar < or = 80​) = 0.4246 ​(Round to four decimal places as​ needed.) b. What is the probability that...
The lifetime of a certain type of battery is normally distributed with a mean of 1000...
The lifetime of a certain type of battery is normally distributed with a mean of 1000 hours and a standard deviation of 100 hours. Find the probability that a randomly selected battery will last between 950 and 1050 hours
The lifetime of a certain type of battery is normally distributed with mean value 13 hours...
The lifetime of a certain type of battery is normally distributed with mean value 13 hours and standard deviation 1 hour. There are nine batteries in a package. What lifetime value is such that the total lifetime of all batteries in a package exceeds that value for only 5% of all packages? (Round your answer to two decimal places.) hours
Cell phone cost is normally distributed with a mean of $83, and a standard deviation of...
Cell phone cost is normally distributed with a mean of $83, and a standard deviation of $16. For a randomly selected cell phone, find the following: What is the probability that the cost is between $ 90 and $100? What is the cost of the top 2% of users? 4. Do problem 1 for a sample of 10 cell phones.