Question 987202
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*[tex \LARGE \ \ \ \ \ \ \ \ \ \ V(t)\ =\ -15t\ +\ 45]


Since this model gives the volume of water in the tub over time as it is draining, the value of the function at time zero must be the capacity of a full tub.  Substitute zero for *[tex \Large t] and solve for *[tex \Large V(0)], the volume of water in a full tub.


Once you know the volume of a full tub, you can divide that number by 2 to find the volume of a half-full tub.


Set *[tex \Large -15t\ +\ 45] equal to the volume of a half full tub and solve for *[tex \Large t_{1/2}], the time at which the tub will be half full.


Since the Volume function is a linear function, there is another way to do this.  Set the function equal to zero and then solve for *[tex \Large t_e],  the time when the tub will be empty.  Since the function is linear, the tub will be half-empty when half the time to empty it completely has passed.  I recommend that you solve this both ways to verify.


Part of your particular problem with mathematics is that you either cannot, or refuse to, read and follow written instructions.  I refer to the very clear instruction on the page where you posted these questions that says "One problem per submission".


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it

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*[tex \LARGE \ \ \ \ \ \ \ \ \ \