Question

David's optometrist sold him a bottle of eyeglass cleaner containing 30 ml of glasscleaning solution. assuming there are 20 drops per milliliter, and assuming proper cleaning requires 3 drops of glass cleaner on each side of each lens, what is the maximum number of times david can properly clean his glasses before he must buy a new bottle of eyeglas

Answer 1

Each complete cleaning requires 6 drops of cleaner. Let's convert that to ml:

6 drops 1 ml 3 ml cleaner
----------- * ------------- = ------------------- = 0.3 ml cleaner per cleaning
20 drops 10 cleanings

Recall that 1 bottle contains 30 ml cleaning fluid.

How many cleanings is one bottle of fluid good for?

1 bottle 0.3 ml
----------- = ----------- => x = 100 cleanings/bottle
x 30 ml