Answer:
A sample of 179 is needed.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
That is z with a pvalue of 
, so Z = 1.44.
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So
Rounding up
A sample of 179 is needed.
Answer: A
Step-by-step explanation:
Answer: 120
Step-by-step explanation:
Given : The league championship 800 meter race has 6 runners.
The number of positions = 3
Since order matters here , so we use Permutation.
The permutation of n things taking r at a time is given by :-
Then, the number of different ways they place first, second, and third :_
Hence, they can place first, second, and third in 120 different ways .
17. Area of triangle: 1/2bh
1/2 * 12 * 15
1/2 * 180
=90 cm^2
18. Area of trapezoid: 1/2 h (b1 + b2)
1/2 * 8 ( 12 + 15.4)
4 * 27.4
= 109.6 cm^2
The answer is A. -7/40.
1. Make sure the (the denominators) are the same
2. Subtract the (the numerators). Put the answer over the same denominator.
<span> 3. Simplify the fraction (if needed)
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