According to a report from a business intelligence​ company, smartphone owners are using an average of 18 apps per month

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According to a report from a business intelligence​ company,
smartphone owners are using an average of 18 apps per month. Assume
that number of apps used per month by smartphone owners is normally
distributed and that the standard deviation is 4 Complete parts​
(a) through​ (d) below. Question content area bottom
Part 1 a.
If you select a random sample of 25 smartphone​ owners, what is
the probability that the sample mean is between 17.5 and 18.5​?
Answer: 0.471 ​(Round to three decimal places
as​ needed.)
Part 2 b.
If you select a random sample of 25 smartphone​ owners, what is
the probability that the sample mean is between 17 and 18?
Answer 0.394 ​(Round to three decimal places
as​ needed.)
c. If you select a random sample of 144 smartphone​ owners, what
is the probability that the sample mean is between 17.5 and
18.5?
Answer 0.866 (Round to three decimal places as​
needed.)
d. Explain the difference in the results of​ (a) and​ (c).
The sample size in​ (c) is greater than the sample size in​ (a),
so the standard error of the mean​ (or the standard deviation of
the sampling​ distribution) in​
(c) is ▼(Greater or Less) than in​ (a).
As the standard error ▼(increases or
decreases) values become more concentrated around
the mean.​
Therefore, the probability that the sample mean will fall close
to the population mean will always ▼(increase or
decrease) when the sample size increases.