Directions Put your name at the top of a blank sheet of paper. There are 11 word problems around the room. You may start at any problem and do not have to go in order. Make sure to label each problem, show all work and circle final answers! No more than 2 students at each problem at one time.

Exponential Word Problems

#1 Suppose a Zombie virus has infected 20 people at our school. The number of zombies doubles every hour. How many zombies are there in 1 day?

#2 A car purchased for $15000 today will depreciate by 7% each year. How much can you expect to sell the car for in 10 years?

#3 For each equation below, give the following: a)Does the equation represent growth or decay? b)What is the y-intercept? c)What is the percent of increase or decrease? Y = 3(.5) x Y = 0.5(1.25) x

#4 Suppose the half-life of a chemical substance is 14 days. Write a model to show the exponential decay of 50-mg substance and find how much of the substance is remaining after 28 days.

#5 Suppose the half life of 260 bacteria cells is 4 days. How many bacteria would remain after 8 days?

#6 Your baby brother has an ear infection. The doctor said there are probably 50,000,000 bacteria in his left ear. The penicillin the doctor prescribed will kill 7% of the bacteria every 6 hours. How many bacteria will be in your brother’s ear in 1 week?

#7 Find the balance of a checking account that has $6,500 compounded annually at 9% for 4 years.

#8 Find the balance of a savings account that has $54,000 compounded quarterly at 12% for 9 years.

#9 Write an exponential function for the graph that includes (1, 4) and (6,10). Round to the hundredths place.

#10 The population of Mullentown grows at a rate of 5% per year. If the population in 1999 was 125,000 what would the predicted population be for 2015?

#11 On January 1, 2013, the price of gasoline was $3.15 per gallon. If the price of gasoline increased by 0.5% per month, what was the cost of one gallon of gasoline, to the nearest cent, on January 1 one year later?