The average battery life of 2800 manufactured cell phones is recorded and normally distributed. the mean battery life is 12 hours with a standard deviation of 1.3 hours. find the number of phones who have a battery life in the 12 to 13.3 range. ∗ *round your answer to the nearest integer. **do not include commas in your answer.

The number of phones is 956

Step-by-step explanation:

* Lets explain how to solve the problem

- The average battery life of 2800 manufactured cell phones is

  recorded and normally distributed

∴ n = 2800

- The mean battery life is 12 hours

∴ μ = 12

- The standard deviation of 1.3 hours

∴ σ = 1.3

- We need P(12 ≤ x ≤ 13.3) to find the number of phones who

  have a battery life in the 12 to 13.3 range

∵ z-score = (x - μ)/σ

∵ x = 12 , μ = 12 , σ = 1.3

∴ z = (12 - 12)/1.3 = 0

- Use the standard normal distribution table

∴ The corresponding area = 0.50000

∵ x = 13.3 , μ = 12 , σ = 1.3

∴ z = (13.3 - 12)/1.3 = 1

- Use the standard normal distribution table

∴ The corresponding area = 0.84134

∴ P(12 ≤ z ≤ 13.3) = 0.84134 - 0.50000 = 0.34134

∵ P(12 ≤ z ≤ 13.3) = P(12 ≤ x ≤ 13.3)

∴ P(12 ≤ x ≤ 13.3) = 0.34134

∵ The number of phones is 2800

∵ The probability of a battery life in the range 12 to 13.3 is 0.34134

∴ The number of phones who have a battery life in this range is

   2800 × 0.34134 = 955.752 ≅ 956 phones

* The number of phones is 956

need more information

step-by-step explanation:

a

step-by-step explanation:

when a number is between two straight lines it means the absolute value.

to find absolute value you need to know how many numbers is that number away from 0.

when finding absolute value the number will always come out positive

so absolute value of -3 is 3

absolute value of 3/2 is 3/2

absolute value of -2 is 2

absolute value of 3.5 is 3.5

absolute value of -1 is 1

now put these numbers in order:

a)   |-1|, |3/2|, |-2|, |-3|, |3.5|