Answer:
C
Step-by-step explanation:
Using sum/difference to product identity
• sin x - sin y = 2 cos(
) sin (
)
with x = 4Θ and y = 2Θ
Then
sin(4Θ) - sin(2Θ)
= 2 cos(
) sin(
)
= 2cos(3Θ)sinΘ → C
Answer:
The required sample size for the new study is 801.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
The margin of error is:

25% of all adults had used the Internet for such a purpose
This means that 
95% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
What is the required sample size for the new study?
This is n for which M = 0.03. So






Rounding up:
The required sample size for the new study is 801.
If right is supposed to be eight then answer is 81