Question

The student union at school has MP3 players pre-loaded with audio and digital books to check out. When the student starts downloading new books at 9:00 am, there are 15 already loaded. When he checks at noon, there are 30 books completely loaded. Assuming that the computer downloads books at a consistent rate, how many complete books will have downloaded at 3:00 pm?

Write a function of books downloaded, y, based on time passed, x (in hours), as well as the total number of books that will be completed by 3:00 pm.

A
y = 10x + 5; 45 complete books


B
y = 15x + 15; 65 complete books


C
y = 5x + 15; 45 complete books


D
y = 15x + 10; 100 complete books

Answer 1

The answer is b because over time the 5x will turn into 65 books

Answer 2

The correct option is C. The function should be:

y = 5x + 15

This function gives the correct number of books downloaded after 3 hours, and the slope is also 5 books per hour.

The other options are incorrect.

Option A: y = 10x + 5. This function does not give the correct number of books downloaded after 3 hours.

Option B: y = 15x + 15. This function gives the correct number of books downloaded after 3 hours, but the slope is not 5 books per hour.

Option D: y = 15x + 10. This function does not give the correct number of books downloaded after 3 hours.