what is the answer to this ?

Question

dara works in the clothing department of a large store. when she began her shift at 4p.m.,the register showed sales of $10,550. when she clocked out at 9p.m.,the register showed sales of $40,620.

Answer 1

I see you posted this under "Calculating Average Rates of Change", so I'm assuming that's what you are looking to solve this problem for since there isn't an actual question stated for this problem...?

If that is the case, then let's first note that the average rate of change in this problem is the change in the value of a quantity (sales) over an interval of time divided by the change in this interval of time.

Let ƒ(t) represent the sales at a certain time, then the average rate of change of the function ƒ with respect to time (t), is represented by the following formula:

   average rate of change = Δƒ(t) / Δt = [ ƒ(t₂) - ƒ(t₁) ] / (t₂ - t₁) 

Given:     at time t₁= 4 p.m., the sales at that time were ƒ(t₁)= 10,550

              at time t₂= 9 p.m., the sales at that time were ƒ(t₂)= 40,620

Plug these values into the formula above to obtain the average rate of change.

   average rate of change = (40,620 - 10,550) / (9 - 4) = (30,070) / (5) = 6,014

Thus, the average rate of change of the store's sales over this 5 hour shift was $6,014 per hour.