ALGEBRA ONE WORD PROBLEM NUMBER 3

Question

A group of scientists studied the affect of a chemical on various strains of bacteria. Strain A started with 12000 cells and decreased at a constant rate of 3000 cells per hour after the chemical was applied. Strain B started with 4000 cells and decreased at a constant rate of 2000 cells per hour after the chemical was applied. When will the strains have the same number of cells? Explain.

Answer 1

Form an equation for strain A using the information provided 

 

A = 12,000-3,000t

 

Form one for strain B the same way 

 

B = 4000- 2,000t

 

Since we are looking for the time at which strains have the same number of cells we need to equate both the equations and solve for t

 

12,000 - 3,000t = 4,000 - 2,000t

 

3,000t - 2,000t = 12,000-4,000

 

1,000t = 8,000

 

t= 8

 

The strains will have the same number of cells after 8 hours.