Question

According to the most recent medical analysis reports, each time an individual person participates a crowd gathering event, there is a 40% chance this individual will contract a certain disease.

(B1) If 7 separate individuals enter a crowd gathering event, what is the probability that none of these 7 individuals contract this disease?

(B2) If 7 separate individuals enter a crowd gathering event, what is the probability that at least half of these 7 individuals contract this disease?

The new research finds that wearing effective protective gears such as masks can reduce the above reported contraction rate from 40% to 5%.

(B3) If 10 separate individuals who wear effective protective gears enter a crowd gathering event, what is the probability that none of these 10 individuals contract this disease?

(B4) If 10 separate individuals who wear effective protective gears enter a crowd gathering event, what is the probability that at least half of these 10 individuals contract this disease?

Answer 1

40% contrating disease/ 60% not contracting disease

B1 : you have to calculate the probality as individual events independent of each other
7 separated individuals not contracting the sisease

B2: It will be the same as before note that they are asking for "at least" meaning that you do not need to calculate the people that did not contract the deasises

depending how you chose to see half

4/3 = 1/4 1/4 1/4 1/4

3/4 = 1/4 1/4 1/4

5% contrating disease/ 95% not contracting disease

both casese will be as the above individual provabilities independant of each other

B3)

B4