Final answer:
The number of people who have heard the rumor after 5 days is 800.
Step-by-step explanation:
To find the number of people who have heard the rumor after 5 days, we need to determine how the number of people doubles each day.
Given that the rumor starts with 50 people, we can calculate the number of people who have heard the rumor after each day:
- Day 1: 50 people
- Day 2: 50*2 = 100 people
- Day 3: 100*2 = 200 people
- Day 4: 200*2 = 400 people
- Day 5: 400*2 = 800 people
Therefore, the number of people who have heard the rumor after 5 days is 800. The correct answer is A. 400.