The selling price of a house dropped from $250,000 to $210,000 over a period of 5 years. what percent did the selling price decr
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:
1.60
Step-by-step explanation:
Assuming that this is a cylindrical pipe, the area can be determined by applying the formula for calculating the area of a circle.
i.e Area =
So that,
for the inner part of the pipe,
r =
=
= 2.5 feet
Area of the inner part of the pipe =
= 3.14 x
= 19.625
Are of the inner part of the pipe is 19.63 .
Total diameter of the pipe = 5 + 0.2
= 5.2 feet
r =
= 2.6 feet
Area of the pipe =
= 3.14 x
= 21.2264
Area of the pipe is 21.23 .
Thus the cross sectional area = Area of the pipe - Area of the inner part of the pipe
= 21.2264 - 19.625
= 1.6014
The cross sectional area of the cement pipe is 1.60 .