A.)Write a Model for the Weight of a Human Embryo After X Days

Name: ______Date: ______

Exponential Growth and Decay

1. From the time the average human embryo is first conceived, it weighs .3 ounces. It then grows (weight gain) approximately 2.15% each day.

a.)Write a model for the weight of a human embryo after x days.

b.)What is the weight after 50 days?

c.)What is the weight after 40 weeks?

(about 7.24 lbs)

1. The initial charge on a AAA battery is 1250 kilowatts per ohm. A typical AAA battery loses its charge at a rate of 3% per week.

a.)Write a model for the charge of the battery after x weeks.

b.)What will the charge of the battery be after 12 weeks?

c.)How long will it take for the battery to have a charge less then 500 kilowatts per ohm?

Y1=500/1250, Y2 =(.97)x: or log(.4)/log(.97)

1. Assume you bought Mickey Mantle’s rookie baseball card at an auction in 1980 for $50 and the value of the card appreciates 4.2% per year. How much will the card be worth in 2010?

1. Assume $25,000 is deposited into an account that pays 4% annual interest, compounded annually. What is the balance in the account after 12 years?

1. What is the balance in the account after 20 years if the interest (from problem 4) was compounded monthly?

1. A large pool has a leak that loses water at a rate of 3% per day. If the volume of the water in the pool is currently 250 gallons, how much water will be in the pool in 3 weeks?

1. A brand new Chevy Tahoe costs $52,000. It depreciates at a rate of 2.1% per year. How much will the Tahoe be worth in 9 years?

1. The Chevy Cavalier depreciates approximately 4.5% every year. If you’re pricing a used Cavalier that is 7 years old and it’s current value is $800, how much was the car worth brand new?

or

1. How much must you invest into a CD at 7% annual interest, compounded annually, if you want to have $115,000 to pay for your child’s education 16 years from now?

1. $2250 is deposited into an account that pays 6% annual interest, compounded quarterly. Find the balance after ten years.

1. How much must you deposit in an account that pays 3.2% annual interest, compounded weekly, to have a balance of $60,000 after 5 years?

1. Assume you had 12,000 active brain cells the Friday before spring break and also assume that you didn’t exercise your brain cells at all over the break. If your brain cells depreciated at a rate of 1.6% every 12 hours, how many brain cells do you have left 10 days later?

1. Assume $25,000 is deposited into an account that pays 4% annual interest, compounded continuously. What is the balance in the account after 12 years?

1. Assume that you now have $45,000 in an account that has been losing 2.5% compounded continuously. This money has been left untouched for 7 years and 3 months. What was the original amount in the account?

, or