This question is solved using the central limit theorem, giving an answer of:
Fourth option, approximately normal with mean of 140 seconds and standard deviation of 10 seconds.
Central Limit Theorem
The Central Limit Theorem establishes 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
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
Mean of 140, standard deviation of 20, sample of 4:
By the Central Limit Theorem, the distribution is approximately normal.
Mean is the same, of 140.
, thus:
Thus, the correct answer is:
Fourth option, approximately normal with mean of 140 seconds and standard deviation of 10 seconds.
For another example of the Central Limit Theorem, you can check brainly.com/question/15519207