Assume that 8% of people are left-handed. We select 6 people at random. a) How many lefties do you expect? b) With what standard deviation? c) If we keep picking people until we find a lefty, how long do you expect it will take?

a) 0.48

b) 0.6645

c) 12.5

Step-by-step explanation:

For each person, there are only two possible outcomes. Either they are left-handed, or they are not. The probabilities of each person being left-handed are independent. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

The expected value of the binomial distribution is:

The standard deviation of the binomial distribution is:

The number of trials expected to find r sucesses is given by

In this problem we have that:

Assume that 8% of people are left-handed. We select 6 people at random.

This means that

a) How many lefties do you expect?

b) With what standard deviation?

c) If we keep picking people until we find a lefty, how long do you expect it will take?

Number of trials to find 1 success. So

1/4 and 8/3 because:

the reciprocal if 4 is 1/4 because 4 is used as 4/1 and the opposite of that is 1/4. the opposite of 3/8 is 8/3 so that is the answer.

answer: 42

use a calculator to find that 845/73 = 11.575

the whole part of the answer is 11. multiply this by 73 to get 11*73 = 803.

subtract that result from 845 to get 845 - 803 = 42