Answer:
The Chang family = 25 hours, The Davis family = 35 hours
Step-by-step explanation:
The given information is as follow
The Chang family = 15L/h
The Davis family = 40L/h
Total time for both sprinklers = 60 hours
Total water output = 1775 L
From this information we can derive a set of simultaneous equations to help us find our answer.
We need to find the following information
The time for the Chang family, taken as t1
The time for the Davis family, taken as t2
From this we derive the following set of equations
1) t1 + t2 = 60 hours ----- <em>(This is derived from the total time for both sprinklers)</em>
2) 15(t1) + 40(t2) = 1775 ---- <em>(This is derived from total water output based on time for each sprinkler)</em>
<em />
Solving these simultaneously we get following equation
t1 = 60 - t2 - <em>equation 1</em>
15(t1) + 40(t2) = 1775 - <em>equation 2</em>
15 (60 - t2) + 40(t2) = 1775 - <em>equation 3 (combining equation 1 & equation 2)</em>
900 - 15(t2) + 40(t2) = 1775 -------- solving the equation 3
25(t2) = 1775 - 900
<u>t2 = 35</u>
<u>t1 = 25</u>
