Question

Assume that 1 mL of water contains 20 drops. How long, in hours, will it take you to count the number of drops in 4.21 gal of water at a counting rate of 10 drops/sec? 1 gal = 3.785 L. (3 significant figures, do not use scientific notation)

Answer 1

8.85 hours (3 sf)

Step-by-step explanation:

1 gal = 3.785 L

4.21 gal = x

x = 4.21 * 3.785 = 15.935 L

The relationship between mL and L is given as;

1000 mL = 1 L

x = 15.935L

x = 15.935 * 1000 = 15935 mL

The relationship between number of drops and mL is given as;

1 mL = 20 drops

15935 mL = x

x = 318 700 drops

The rate is 10 drops per sec

Rate = Number of drops / time

10 = 318700 / time

time = 31870 seconds

The question says to convert present the answer in hours so we convert time to hours by dividing the answer by 3600

Time = 31870 / 3600 = 8.85 hours (3 sf)