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Josephine can correct her students' test papers in 9 hours, but if her teacher's assistant helps, it would take them 7 hours. How long, in hours and minutes, would it take the assistant to do it alone? (Write your answer in mixed units. Enter a zero in any unneeded blanks.)

Respuesta :

Using the together rate, it is found that it would take the assistant 31 hours and 30 minutes to do it alone.

What is the together rate?

It is the sum of each separate rate.

In this problem, the rates are given as follows:

  • Josephine: 1/9.
  • Assistant: 1/x.
  • Together: 1/7.

Hence:

[tex]\frac{1}{9} + \frac{1}{x} = \frac{1}{7}[/tex]

[tex]\frac{x + 9}{9x} = \frac{1}{7}[/tex]

[tex]9x = 7x + 63[/tex]

2x = 63

x = 31.5.

It would take the assistant 31 hours and 30 minutes to do it alone.

More can be learned about the together rate at https://brainly.com/question/25159431

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