Answer:
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