Question

The recovery rate from a flu is 0.6. For 4 people having this flu, find the probability that:
(a) All will recover:
(b) Exactly 2 will recover:
(c) At least 2 will recover:
Assume independence Answers should be exact

Answer 1

a. All recover:

(.6)^4

b. Exactly 2 recover:

This follows a binomial distribution.

The formula for this is:

xCy * (p)^x * (p)^(x-y)

4C2 * (0.6)^4(0.4)^2

Answer 2

c. At least 2 recover:

P(Exactly 2) + P(Exactly 3) + P(Exactly 4)

Or, 1-P(Exactly 0) + P(Exactly 1).

Thus,

1-(1-0.6^4) + 4C1 * (0.6)^1 * (0.4)^3

Answer 3

can you explain this a little bit better because when i try to get the answer no matter which way i do it i cant get the correct answer for b and c