Answer:
A sample size of 385 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 = 1.96.
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.
You feel that a reasonable estimate of the standard deviation is 10.0 hours.
This means that 
What sample size is needed so that the expected margin of error of your estimate is not larger than one hour for 95% confidence?
A sample size of n is needed. n is found when M = 1. So
Rounding up:
A sample size of 385 is needed.
Answer:
x = 16
y = 13.8
Step-by-step explanation:
Answer:
39.25 cubic feet of paint will be needed by Ellis.
Step-by-step explanation:
Step-by-step explanation:
Volume of a cylinder:
The volume of a cylinder of radius r and height h is given by:
V = \pi r^2h = 3.14r^2h
How much paint will Ellis need to paint all the surfaces of the 10 fenceposts?
This is the combined volume of these 10 fenceposts.
They are each 5 feet tall and have a diameter of 1 foot.
Radius is half the diameter, so r = \frac{1}{2} = 0.5. Also h = 5
10 fenceposts:
Each has the same volume, so:
V = 10(3.14)r^2h = 31.4(0.5)^2(5) = 39.25
39.25 cubic feet of paint will be needed by Ellis.
hope this helps
Answer: 20
Step-by-step explanation:
