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Jeremy sells a magazine that is produced in order to raise money for homeless people.

The probability of making a sale is, independently, 0.4 for each person he approaches.
Given that he approaches 10 people, find the probability that he will make:
(i) 2 sales
(li) 8 sales.

1 Answer

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(i) Probability of making 2 sales: Approximately 0.1209

(ii) Probability of making 8 sales: Approximately 0.1209

To find the probabilities of Jeremy making 2 sales and 8 sales, we can use the binomial probability formula:

P(X=k) = (nCk) * p^k * (1-p)^(n-k)

Where:

P(X=k) is the probability of exactly k successes

n is the number of trials or people approached

k is the number of successes or sales

p is the probability of success on each trial (probability of making a sale)

(nCk) is the binomial coefficient, which represents the number of ways to choose k successes from n trials

(i) Probability of making 2 sales:

n = 10 (number of people approached)

k = 2 (number of sales)

p = 0.4 (probability of making a sale)

P(X=2) = (10C2) * 0.4^2 * (1-0.4)^(10-2)

Using the binomial coefficient formula:

(10C2) = 10! / (2! * (10-2)!) = 45

P(X=2) = 45 * 0.4^2 * 0.6^8 = 0.1209

Therefore, the probability that Jeremy will make 2 sales is approximately 0.1209.

(ii) Probability of making 8 sales:

n = 10 (number of people approached)

k = 8 (number of sales)

p = 0.4 (probability of making a sale)

P(X=8) = (10C8) * 0.4^8 * (1-0.4)^(10-8)

Using the binomial coefficient formula:

(10C8) = 10! / (8! * (10-8)!) = 45

P(X=8) = 45 * 0.4^8 * 0.6^2 = 0.1209

Therefore, the probability that Jeremy will make 8 sales is also approximately 0.1209.

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