He ages of mark and adam add up to 28 years total. mark is 20 years older than adam. how many years old is adam
1 answer:
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Part a)
The simple random sample of size n=36 is obtained from a population with
and
The sampling distribution of the sample means has a mean that is equal to mean of the population the sample has been drawn from.
Therefore the sampling distribution has a mean of
The standard error of the means becomes the standard deviation of the sampling distribution.
Part b) We want to find
We need to convert to z-score.
Part c)
We want to find
We convert to z-score and use the normal distribution table to find the corresponding area.
Part d)
We want to find :
We convert to z-scores and again use the standard normal distribution table.