Randomly selected students participated in an experiment to
Solution
Note that
Lower Bound = X - z(alpha/2) * s / sqrt(n)
Upper Bound = X + z(alpha/2) * s / sqrt(n)
where
X = sample mean = 60.4
z(alpha/2) = critical z for the confidence interval = 2.575829304
s = sample standard deviation = 10.3
n = sample size = 40
Thus,
Lower bound = 56.20507396
Upper bound = 64.59492604
Thus, the confidence interval is
( 56.20507396 , 64.59492604 ) [ANSWER]
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OPTION D: Yes, because the confidence interval includes 60 seconds. 60 is between those two numbers.
