Question

1.The probability that a patient recovers from a delicate heart operation is 0.9. What is the probability that exactly 5 of the next 7 patients

having this operation survive?

2. On the average a secretary makes 2 typing errors per page. What is the probability that he makes

a) Four or more errors on the next page?

b) No errors?

Answer 1

Solution:

1. The probability that a patient recovers from a delicate heart operation is 0.9. What is the probability that exactly 5 of the next 7 patients having this operation survive?

Answer: Let x be the number of patients having the operation survive. Now using the binomial distribution, we have:

Therefore, the probability that exactly 5 of the next 7 patients having this operation survive is 0.1240

2. On average a secretary makes 2 typing errors per page. What is the probability that he makes

a) Four or more errors on the next page?

Answer: Let x be the number of typing errors per page. Then the random variable x follows a Poisson distribution with

We have to find:

We know that:

  

  

b) No errors?

Answer:

We have to find: