Question

A phone company surveys a sample of current customers to determine if they use their phones most often to text or use the Internet. They sort the data by payment plans, as shown below.
Plan A: 27 text, 21 Internet
Plan B: 13 text, 10 Internet

Answer the questions to determine a conditional probability.

How many customers are on payment plan B?

____ customers

How many of the customers on plan B text?

____ customers

What is the probability that a randomly selected customer who is on plan B uses the phone most often to text? Give the answer in fraction form.

_____

Answer 1

Answer:

23 customers

13 customers

13/23

Step-by-step explanation:

Answer 2

Answer:

• 23 are on plan B
• 13 on plan B text
• 13/23 is the probability a customer on plan B will text

Step-by-step explanation:

Assuming the categorization is mutually exclusive (customers either text or internet, but not both), the total number of Plan B customers in the sample is the sum of those in each category:

.... 13 + 10 = 23 . . . . plan B customers

The problem statement tells you

... 23 plan B customers text

Since 13 out of 23 customers surveyed use the phone for text, the empirical probability that a plan B customer will use the phone for texting is ...

... 13/23 . . . . probability that text is used most