An inverted pyramid is being filled with water at a constant rate of 70 cubic centimeters per second. the pyramid, at the top, has the shape of a square with sides of length 7 cm, and the height is 10 cm. find the rate at which the water level is rising when the water level is 4 cm.

Rate of change in height of the water level is 2.91 cm per second.

Step-by-step explanation:

Height of the inverted pyramid = 10 cm

Length of the square base = 7 cm

If water is filled up to the level of h cm then the volume of water up to height h will be

V =

V =

It is given that rate of water is filling with 70 cubic centimeters per second.

From two similar triangles in the figure attached,

By replacing the value of h,

V =

V =

V =

Now we integrate the equation with respect to time 't'

70 =

For h = 7 cm

Therefore, rate of change in height of the water level is 2.91 cm per second.

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First, think of what you know. you know that the number t the end of the equation will need to be subtracted because it is the money he lost from buying the lawn mower. and your first two weeks have negative profit, so that tells you that c and d are wrong. now you can plug any of the weeks into a and b to see which one works. i'll start with plugging week 1 into a.this isn't right because it says your answer for week one should be -90.so now we need to try the same thing with b.this one got you the right answer, (sometimes if you only check with one of the weeks multiple will work so you need to check with more of the weeks, but it worked out fine here)this means that b is the correct answer.let me know if you need more clarification. i hope this : )