Cory, Amanda, and Bryan together need a total of 9 days to finish painting the house. Amanda and Bryan together need 12 days to finish painting. How many days will it take for Cory to paint the house alone?

Respuesta :

The difference between the work rate of three persons and the work rate

of two people, gives the work rate of the third person.

Correct response:

  • The number of days it will take Cory to paint the house alone is 36 days.

Methods used to obtain Cory's rate of work

The duration needed for Cory, Amanda, and Bryan together to finish painting the house = 9 days

The duration needed for Amanda and Bryan together to paint the house = 12 days

Required:

The number of days Cory will take to paint the house alone.

Solution:

Let t₁  represent the time it takes Cory to paint the house alone, let t₂

represent the time it takes Amanda to paint the house alone, and let t₃

represent the time it takes for Bryan to paint the house alone.

The work rate formula is presented as follows

[tex]\displaystyle \frac{1}{t} = \mathbf{ \frac{1}{t_1} +\frac{1}{t_2} +\frac{1}{t_3}}[/tex]

Where;

t = The time it takes to paint the house together = 9 days

Which gives;

[tex]\displaystyle \frac{1}{9} = \frac{1}{t_1} +\frac{1}{t_2} +\frac{1}{t_3}[/tex]

From the question, we have;

The time it takes Amanda and Bryan to paint the house together, is 12 gays, therefore;

[tex]\displaystyle \frac{1}{12} = \mathbf{\frac{1}{t_2} + \frac{1}{t_3}}[/tex]

[tex]\displaystyle \frac{1}{9} = \frac{1}{t_1} + \frac{1}{12}[/tex]

[tex]\displaystyle \frac{1}{t_1} = \frac{1}{9} -\frac{1}{12} = \mathbf{\frac{1}{36}}[/tex]

  • The duration in days it will take Cory to paint the house alone, t₁ = 36 days

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