An item costs $440 before tax, and the sales tax is $30.80.
1 answer:
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Answer:
Step-by-step explanation:
Given that a researcher is trying to decide how many people to survey.
We have confidence intervals are intervals with middle value as the mean and on either side margin of error.
Confidence interval = Mean ± Margin of error
Thus confidence interval width depends on margin of error.
Margin of error =
Thus for the same confidence level and std deviation we find margin of error is inversely proportional to square root of sample size.
Hence for small n we get wide intervals.
So if sample size = 300, the researcher will get wider confidence interval
Answer:
The volume of the ball with the drilled hole is:
Step-by-step explanation:
See attached a sketch of the region that is revolved about the y-axis to produce the upper half of the ball. Notice the function y is the equation of a circle centered at the origin with radius 15:
Then we set the integral for the volume by using shell method:
That can be solved by substitution:
The limits of integration also change:
For x=5:
For x=15:
So the integral becomes:
If we flip the limits we also get rid of the minus in front, and writing the root as an exponent we get:
Then applying the basic rule we get:
Since that is just half of the solid, we multiply by 2 to get the complete volume:
