Liliana wants to start a seventh-grade computer club at Hamden Middle School. She surveyed 20 seventh-grade students at the town park. She asked each student how many hours they spend on their computers each week and obtained the following results:

[tex]8, 15, 0, 11, 12, 13, 16, 13, 0, 4, 17, 14, 30, 13, 5, 12, 1, 13, 12, 21[/tex]

What is the ratio of the total number of students who used their computers to the total number of students surveyed?

A. [tex]\frac{2}{20}[/tex] or [tex]\frac{1}{10}[/tex]
B. [tex]\frac{2}{18}[/tex] or [tex]\frac{1}{9}[/tex]
C. [tex]\frac{18}{20}[/tex] or [tex]\frac{9}{10}[/tex]
D. [tex]\frac{18}{2}[/tex] or [tex]\frac{1}{1}[/tex]

Sure, let's solve the problem step-by-step.

Liliana surveyed 20 seventh-grade students about their computer usage. We need to find the ratio of students who used their computers at least once to the total number of students surveyed.

Here’s how you can determine this:

1. Count the Number of Students Who Used Their Computers:
- Go through the list of hours each student spent on their computer.
- Count how many students have non-zero values because a non-zero value indicates that the student spent some time on their computer.

From the list provided:
`[8, 15, 0, 11, 12, 13, 16, 13, 0, 4, 17, 14, 30, 13, 5, 12, 1, 13, 12, 21]`
We have 18 students with non-zero hours.

2. Determine the Total Number of Students Surveyed:
- There are 20 students in the list.

3. Calculate the Ratio:
- The ratio of students who used their computers to the total surveyed students is given by the formula:
[tex]\[
\text{Ratio} = \frac{\text{Number of students who used their computers}}{\text{Total number of students surveyed}}
\][/tex]
- Plug the numbers you’ve counted:
[tex]\[
\text{Ratio} = \frac{18}{20} = \frac{9}{10}
\][/tex]

So, the ratio of students who used their computers to the total number of students surveyed is [tex]$\frac{9}{10}$[/tex].