Answer:


And the 68% confidence interval is given by (91.1186, 97.2814)
Step-by-step explanation:
For this case we know that mean time that visitors stay at a museum is given by:

The standard deviation is given by:
And the standard error is given by:
And we want to interval captures 68% of the means for random samples of 25 scores and for this case the critical value can be founded like this using the normal standard distribution or excel:

We can find the interval like this:

And replacing we got:


And the 68% confidence interval is given by (91.1186, 97.2814)
Answer:
62.17% probability that a randomly selected exam will require more than 15 minutes to grade
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

What is the probability that a randomly selected exam will require more than 15 minutes to grade
This is 1 subtracted by the pvalue of Z when X = 15. So



has a pvalue of 0.3783.
1 - 0.3783 = 0.6217
62.17% probability that a randomly selected exam will require more than 15 minutes to grade
Answer: C
Step-by-step explanation:^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
which class is this because I am in 7th class so that's why I can't give
Answer:
This is jibberish
Step-by-step explanation:
Just language please and thanks