Question

Owen owns a small business selling used books. He knows that in the last week 85 customers paid cash, 4 customers used a debit card, and 12 customers used a credit card. Based on these results, express the probability that the next customer will pay with something other than a debit card as a fraction in simplest form

Answer 1

Ok, so

We got these facts:

The number of customers that paid cash: 85

The number of customers that used a debit card: 4

The number of customers that used a credit card: 12

Now, it would be useful to find the total number of different payments made, which is: 85 + 4 + 12, and this is 101 payment.

Remember that:

Probability = The number of desired outcome/(The number of possible outcome)

The probability that the next customer will pay with something other than a debit card = (The number of customers that used something different than a credit card) / (The total number of different payments made)

So, Probability = (85+12) / 101

And this is Probability = 97/101

For the second question:

We know that the total students asked from eighth are 29. So, the probability that an eighth grader chosen at random will play an instrument other than guitar, will be:

Probability = 22/29