Using the z-distribution, as we are working with a proportion, it is found that the margin of error for the 90% confidence interval is of 0.0524 = 5.24%.
<h3>What is a confidence interval of proportions?</h3>
A confidence interval of proportions is given by:

In which:
is the sample proportion.
The margin of error is given by:

In this problem, the critical value is given as z = 1.645, and since 26 out of 80 students said they would be willing to pay extra:

Then, the <em>margin of error</em> is of:

More can be learned about the z-distribution at brainly.com/question/25890103
Answer: -2x+7y+16
Step-by-step explanation:
1. Distribute 2 through the parentheses
- 4x+6y+3(5-2x)+1+y
- 4x+6y+15-6x+1+y
2. Collect like terms
- -2x+6y+15+1+y
- -2x+7y+15+1
- -2x+7y+16
3. Solution, -2x+7y+16
Answer: a) 8.779 years
b) 8.664 years
<u>Step-by-step explanation:</u>
a)

- A: accumulated amount (balance)
- P: principal amount (original/initial investment)
- r: interest rate (convert to a decimal)
- n: number of times compounded per year
- t: number of years
Given: A = 1800, P = 900, r = 8% = 0.08, n = 3, t = unknown

b)


Answer:
48π in³
Step-by-step explanation:

Plug in the radius 6 in and the height 4 in

Therefore, the volume of the cone is 48π in³.
I hope this helps!