Discover new information and insights with the help of IDNLearn.com. Get step-by-step guidance for all your technical questions from our knowledgeable community members.

Engineers are draining a water reservoir until its depth is only 10 feet. The depth decreases exponentially as
shown in the graph below. The engineers measure the depth after 1 hour to be 64 feet and after 4 hours to be
28 feet. Develop an exponential equation in y=a(6)" to predict the depth as a function of hours draining.
Round a to the nearest integer and b to the nearest hundredth. Then, graph the horizontal line y = 10 and
find its intersection to determine the time, to the nearest tenth of an hour, when the reservoir will reach a
depth of 10 feet.


Sagot :

The draining of the reservoir follows an exponential function

The reservoir will reach a  depth of 10 feet at 7.6 hour

The given parameters are:

[tex]\mathbf{(x,y) = (1,64)(4,28)}[/tex]

An exponential equation is represented as:

[tex]\mathbf{y = ab^x}[/tex]

Substitute [tex]\mathbf{(x,y) = (1,64)(4,28)}[/tex] in [tex]\mathbf{y = ab^x}[/tex]

[tex]\mathbf{64 = ab^1}[/tex]

[tex]\mathbf{64 = ab}[/tex]

[tex]\mathbf{28 = ab^4}[/tex]

Divide [tex]\mathbf{64 = ab}[/tex] and [tex]\mathbf{28 = ab^4}[/tex]

[tex]\mathbf{\frac{ab^4}{ab} = \frac{28}{64}}[/tex]

[tex]\mathbf{b^3 = 0.4375}[/tex]

Take cube roots

[tex]\mathbf{b= 0.76}[/tex]

Substitute [tex]\mathbf{b= 0.76}[/tex] in [tex]\mathbf{64 = ab}[/tex]

[tex]\mathbf{64 = 0.76a}[/tex]

Solve for a

[tex]\mathbf{a = 84}[/tex]

So, the equation is:

[tex]\mathbf{y = 84(0.76)^x}[/tex]

See attachment for the graphs of [tex]\mathbf{y = 84(0.76)^x}[/tex] and y = 10

The point of intersection is: x = 7.6

Hence, the reservoir will reach a  depth of 10 feet at 7.6 hour

Read more about exponential functions at:

https://brainly.com/question/15352175

View image MrRoyal
We value your participation in this forum. Keep exploring, asking questions, and sharing your insights with the community. Together, we can find the best solutions. Discover the answers you need at IDNLearn.com. Thanks for visiting, and come back soon for more valuable insights.