A kayaker travels x miles per hour downstream for 4 hours. On the 6-hour return trip, the kayaker travels 2 mile per hour slower
1 answer:
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Answer:
21
Step-by-step explanation:
Using<em> Simple Random Sampling</em>, we can estimate the sample size by the formula
where
n = sample size
Z = the z-score corresponding to the confidence level 99.5%
S = the assumed standard deviation = 3 seconds
e = margin of error = 2 seconds
<em>It is worth noticing that the higher the confidence level, the larger the sample should be. </em>
The z-score corresponding to a confidence level of 99.5% can be obtained either with a table or the computer and equals
Z = 3.023
Replacing the values in our formula
So the size of the sample should be at least 21.
Answer:
0.9792
Step-by-step explanation:
Data provided in the question:
Average gross sales = $1,240
Standard deviation = $180
sample size = 40
Now,
standard deviation of sample average
=
=
= 28.46
Now,
z value for 1200 = = -1.4,
and,
p value for (z = -1.4) = 0.0808
therefore,
P(average < $1200) = 0.0808
Thus,
probability that the average over the next 40 weekdays will exceed $1,200
= 1 - 0.808
= 0.9792