If every seven digit whole neumber is a possible phone number, except those that begin with 0 or 1, what fraction of telephone numbers begin with 9 and end with 0?

wouldn't it be 1/8 * 1/10 ?

Since the first number cannot be 0 or 1, you have 1/8 probability of getting a 9. The probability of the last number being 0 is 1/10.

The probability of two or more events all occurring is found by multiplying the individual probabilities.

I hope this helps you to understand the process to solve similar problems. Thanks for asking.

To find the fraction of telephone numbers that begin with 9 and end with 0, we first need to determine the total number of 7-digit whole numbers that can be phone numbers.

Since we are working with 7-digit whole numbers, the first digit can be any number from 0 to 9, excluding 0 and 1. So we have 8 choices for the first digit.

The second digit can be any number from 0 to 9, including 0 and 1. So we have 10 choices for the second digit.

Similarly, the third, fourth, fifth, sixth, and seventh digits can also each be any number from 0 to 9, giving us 10 choices for each digit.

Therefore, the total number of possible 7-digit whole number phone numbers is calculated as follows:

8 choices for the first digit × 10 choices for each of the remaining six digits = 8 × 10^6

Now let's determine the number of telephone numbers that begin with 9 and end with 0.

For a number to begin with 9, we have only 1 choice for the first digit, which is 9.

For the remaining six digits, each has 10 choices since they can be any digit from 0 to 9.

Therefore, the total number of telephone numbers that begin with 9 and end with 0 is calculated as follows:

1 choice for the first digit (9) × 10 choices for each of the remaining six digits = 1 × 10^6

To find the fraction, we divide the number of telephone numbers that begin with 9 and end with 0 by the total number of possible phone numbers:

fraction = (number of telephone numbers that begin with 9 and end with 0) / (total number of phone numbers)

fraction = (1 × 10^6) / (8 × 10^6)

The common factor, 10^6, cancels out:

fraction = 1/8

Therefore, the fraction of telephone numbers that begin with 9 and end with 0 is 1/8.