Look at the attachment ;)
Hope this helps!
Answer:
You can wait at the front of the luchline and survey every tenth student.
Step-by-step explanation:
This way it is equal for everyone.
If the center is at (0, 0) and the vertex is at (20, 0), then the distance, a, is the length from the center to the vertex, 20. The distance from the center to the focus is c. The distance from the center to the focus is 16, so c = 16. The formula we use to find the focus is

. We have our c value and our a value, so we will sub in those to find b.

and 256 = 400 - b^2. -b^2 = -144, so b = 12. There you go!
5:8 and 20:32 would be a proportion.
Easy way to find this:
Set up the proportion as a fraction.
Use the cross product property. Multiply the diagonals and if the products of the diagonals are the same, then they are proportional.
Answer:
If 12,000 are put at an account with 2.5% compound interest in 15 years your total would be $17,379.58