Question

The Phillips family and the Peterson family each used their sprinklers last summer.The water output rate for the Phillips family's sprinkler was 35 L per hour.The water output rate for the Peterson family's sprinkler was 15 L per hour.The families used their sprinklers for a combined total of 35 hours, resulting in a total water output of 925 L.How long was each sprinkler used?

Answer 1

Answer:The Phillips family used their sprinklers for 20 hours while The Petersons family used their sprinklers for 15 hours.

Explanation:

Let x = the number of times that the Phillips family used their sprinkler last summer.

Let y = the number of times that the Petersons family used their sprinkler last summer.

The water output rate for the Phillips family sprinkler was 35 L per hour.

This means that the total volume of water from their sprinkler is 35xL

The water output rate for the Petersons family sprinkler was 15 L per hour.

This means that the total volume of water from their sprinkler is 15yL

The families used their sprinklers for a combined total of 35 hours, resulting in a total water output of 925 L. This means

x + y = 35

35x + 15y = 925 - - - - - - - - 2

Substituting x = 35 - y into equation 2

35(35-y) + 15y = 925

1225 - 35y + 15y = 925

- 20y = 925 - 1225 =- 300

y = - 300 / -20 = 15

x = 35 - y = 35 - 15 = 20

The Phillips family used their sprinklers for 20 hours while The Petersons family used their sprinklers for 15 hours.