Answer:
The answer is "0.624"
Step-by-step explanation:
[tex]b = 5x\\\\h = x\\\\ l = 10 \\[/tex]
Using formula:
[tex]V = (\frac{1}{2})(b)(h)(l) \\\\[/tex]
[tex]= \frac{1}{2} \times (5x)\times (x) \times (10)\\\\= 5x\times x \times 5\\\\= 25x^2[/tex]
[tex]\frac{dV}{dt} = 50x \ \frac{dx}{dt} \\\\\text{(where x represents the height in feet and}\ \frac{dv}{dt} = 13\ \frac{ft^3}{min})\\\\\frac{dx}{dt} = (\frac{1}{50})(\frac{1}{x}) \ \frac{dV}{dt}\\\\[/tex]
When the water is 5 inches deep then:
[tex]x = (\frac{5}{12})\ ft\\\\13 =50(\frac{5}{12}) \ \frac{dx}{dt}\\\\13 \times 12 =50(5) \ \frac{dx}{dt}\\\\\frac{13 \times 12}{50 \times 5} = \frac{dx}{dt}\\\\\frac{156}{250} = \frac{dx}{dt}\\\\ \frac{dx}{dt}= 0.624[/tex]
