A small group of employees in a company get viruses on their computers. Every hour, each computer infects one other computer. If it takes 8 hours for 100 computers to be infected, how long would it take for only 50 computers to be infected?

A pen and notebook together cost $1.20. If the notebook costs $1.00 more than the pen, how much does the pen cost?

The pen must cost $0.20

$0.10

To solve this problem, let's break it down step by step:

1. Start with the information given: It takes 8 hours for 100 computers to be infected.

2. Since every infected computer infects one other computer every hour, we can determine the rate of infection as 1 infected computer per hour.

3. Now, we want to find out how long it would take for only 50 computers to be infected, instead of 100.

4. Since the rate of infection remains constant at 1 infected computer every hour, we can set up a proportion to solve for the unknown time.

5. Let "t" represent the time it would take for 50 computers to be infected. We can set up the following proportion:
100 computers / 8 hours = 50 computers / t hours

6. Solve the proportion by cross-multiplying:
100t = 8 * 50
100t = 400

7. Divide both sides of the equation by 100 to solve for "t":
t = 400 / 100
t = 4

8. The answer is t = 4, which means it would take 4 hours for 50 computers to be infected.

Therefore, it would take 4 hours for only 50 computers to be infected.