  # Jay can remember only the area code and the first 3 digits of his friend's phone number. He also knows that the number has 7 digits (not including the area code) and the last digit is not a zero. If Jay were to dial all of the possible numbers and it takes him 21 seconds to try each one, how many hours would it take him (in total) to try each possibility?

Question

Jay can remember only the area code and the first 3 digits of his friend's phone number. He also knows that the number has 7 digits (not including the area code) and the last digit is not a zero. If Jay were to dial all of the possible numbers and it takes him 21 seconds to try each one, how many hours would it take him (in total) to try each possibility?

check_circleExpert Solution
Step 1

The total number of 4 digits and last digit is not a zero is,

1st digit is 0 to 9

2st digit is 0 to 9

3st digit is 0 to 9

Last digit is 1 to 9

The total number of 4 digits is,

Step 2

The number of hours would it take him (in ...

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