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Hospital records show that among all patients suffering from a certain disease,

ID: 3170300 • Letter: H

Question

Hospital records show that among all patients suffering from a certain disease, 70% die of it(so, 30% will recover? Write out the probability that among 100 randomly selected patients, exactly 40 will recover? The average number of homes sold by the Acme Realty company is 2 homes per day. What is the probability that exactly 3 homes will be sold tomorrow? Suppose that the SAT Math score (in a certain region) follows a normal distribution with mean 550 and standard deviation 85. Your score is 620. Find your ranking (the percentage of all students whose scores are below your).

Explanation / Answer

7. It follows binomial distribution

with parameters n= 100

p=0.3

We need to find Probability that only 40 will recover out of 100

i.e. P(X=40) = 100C40 (0.3)^40(0.7)^60

where nCk = n!/(k!)(n-k)!

Hence  P(X=40) = 100C40 (0.3)^40(0.7)^60 is the answer