Word Problems

Question

Suppose that the water level of a river is 34 feet and that it is receding at a rate of 0.5 foot per day. Write an equation for the water level, L, after d days. In how many days will the water level be 26 feet?Suppose that the water level of a river is 34 feet and that it is receding at a rate of 0.5 foot per day. Write an equation for the water level, L, after d days. In how many days will the water level be 26 feet?

Answer 1

Here we can form equation using slope intercept form

 

y= mx+b

 

y= water level=L

x = Days=D

 

m=slope=rate of change =-0.5

b=y-intercept=initial water level= 34

 

equation for the water level, L, after d days

 

L=-0.5D + 34

 

how many days will the water level be 26 feet?

L=26

 

26=-0.5D+34

 

subtract 34 to both sides

26 - 34 = -0.5D + 34 - 34

-8 = -0.5D

 

Divide both side by -0.5

 

16= D

 

So it will take 16 days