Salesman success rate is 0.35. Find probability that >=75% will buy product.

[sarahlee]

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Section 14 Probability 2

14) A salesman has a success rate of 0.35, i.e. the probability that a passerby will buy the product after his salespitch is 0.35. What is the probability that there are 3 or more passersby out of 4 buying the product after his salespitch? Assume the 4 passersby's decisions are independent of each other.
Answer: P(3 or more passersby out of 4 buying the product after his salespitch) =

 

[stapel]

Section 14 Probability 2

14) A salesman has a success rate of 0.35, i.e. the probability that a passerby will buy the product after his salespitch is 0.35. What is the probability that there are 3 or more passersby out of 4 buying the product after his salespitch? Assume the 4 passersby's decisions are independent of each other.
Answer: P(3 or more passersby out of 4 buying the product after his salespitch) =

The simpler option, of course, is to find the probabilities that none or only one will. So you found the probability of failure, multiplied for the two cases, and... then what? Where are you stuck?

Please be complete. Thank you!

 

[m2017]

Section 14 Probability 2

14) A salesman has a success rate of 0.35, i.e. the probability that a passerby will buy the product after his salespitch is 0.35. What is the probability that there are 3 or more passersby out of 4 buying the product after his salespitch? Assume the 4 passersby's decisions are independent of each other.
Answer: P(3 or more passersby out of 4 buying the product after his salespitch) =

The chances of all 4 buying are 0.35^4.

The chances of 3 buying and one not buying are 0.35*0.35*0.35*0.65

Buy 3 people can be chosen in 4C3 ways which is 4 so the answer is (0.35*0.35*0.35*0.65)*4+(0.35*0.35*0.35*0.65)

 

[HallsofIvy]

Binomial Distribution


Surely someone has mentioned that in your class?