The lifetime of a certain type of battery has a mean value 20 hours and standard deviation 3 hours. A bulk package of these batteries contains 40 randomly selected batteries. The distribution of average life time i g

The distribution of average life time is approximately normallyl distributed with mean 20 hours and standard deviation of 0.4743 hours

Step-by-step explanation:

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean and standard deviation , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean and standard deviation .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem

The distribution of average life time is approximately normallyl distributed with mean 20 hours and standard deviation of 0.4743 hours

1. x> -5

2. x< 8

step-by-step explanation:

1. 2x> -10

divide by 2 from both sides of equation.

2x/2> -10/2

simplify, to find the answer.

-10/2=-5

x> -5 is the correct answer.

2. 3x< 24

divide by 3 from both sides of equation.

3x/3< 24/3

simplify, to find the answer.

24/3=8

x< 8 is the correct answer.

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