Question

26 customers are eating dinner at a local diner. Of the 26 customers, 20 order coffee, 8 order pie, and 7 order coffee and pie. what is the probability that a customer orders coffee or pie?

Answer 1

The probability that a customer orders coffee or pie is 21/26 or 0.8

Explanation:

It is given that,

26 customers are eating dinner at a local diner.

The total number of customers = 26

Of the 26 customers,

• 20 order coffee
• 8 order pie and
• 7 order coffee and pie.

To find the probability that a customer orders coffee or pie :

The formula used is P(A or B) = P(A) + P(B) - P(A∪B)

Here,

• The event A is ordering coffee.
• The event B is ordering pies.

P(coffee) = No.of customers order coffee / Total customers

⇒ 20 / 26

P (pie) = No.of customers order pie / Total customers

⇒ 8 / 26

P (coffee and pie) = No.of customers order both / Total customers

⇒ 7 / 26

P (coffee or pie) = P(coffee) + P(pie) - P (coffee and pie)

⇒ 20/26 + 8/26 - 7/26

⇒ 21/26

⇒ 0.8

∴ The probability that a customer orders coffee or pie is 21/26 or 0.8