Answer: 26 cups will fit in a dispenser that is 30 cm high.
Explanation:
First of all, we know that the first cup in the stack (the bottom cup) will be ten centimeters high, and we know that for every cup that is added on top of that, .8 centimeter will be added to the height. So, if we want to find how many cups will be in the dispenser we do this simple math:
30 - 10 = 20 Because the first cup is ten centimeters, we have to subtract that from the dispenser height.
20/.8=25 To find how many cups will be stacked on top of the first cup, we divide the remaining height by .8, the height of every other cup.
Now that we know that there will be 25 cups stacked on top of the first, we add the bottom cup to the rest of them.
25 + 1 = 26 Cups.