Answer:
a. n=4148
b. n=3909
c. The sample size is smaller if a known proportion from prior study is used. The difference in sample sizes is 239
Step-by-step explanation:
a. For sample where no preliminary estimate is given, the minimum sample size is calculated using the formula:

Where:
Margin of error
is the assumed proportion
#Let p=0.5, substitute in the formula to solve for n:

Hence, the minimum sample size is 4148
b. If given a preliminary estimate p=0.38, we use the same formula but substitute p with the given value:

Hence, the minimum sample size is 3909
c. Comparing the sample sizes from a and b:

Hence, the actual sample size is smaller for a known proportion from prior a prior study.
It is a good idea to check to see if your answer is reasonable because a. if your answer is reasonable, you have probably done the problem correctly.
Answer: The first one is = 27.5
1/3 * 25 * 3.3 = 27.5
Answer:
Volume = 2520 cm^3.
Step-by-step explanation:
The volume of a pyramid = 1/3 * area of the base * height.
The base of this pyramid is a triangle and its area
= 1/2 * 18 * 24 cm^2 so the volume of the pyramid is:
1/3 * 1/2 * 18 * 24 * 35
= 2520 cm^3.