The amount of water used to take a shower is directly proportional to the amount of time that the shower is in use. A shower lasting 18 minutes requires 10.8 gallons of water. Find the amount of water used in a shower lasting 4 minutes.

The answer to your question is 2.4 gallons of water.

Explanation:

Data

Volume = time

10.8 gallons = 18 min

x                   = 4 min

Process

1.- Write a proportion to solve this problem

                  10.8 gallons 18 min

                    x    gallons   4 min

2.- Simplification

                    x = (4 x 10.8) / 18

                    x = 43.2 / 18

3.- Result

                    x = 2.4 gallons                    

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)