math
posted by alex on .
5. At 2pm the number of bacteria in a colony was 100, by 4pm it was 4000. Write an exponential function to model the population y of bacteria x hours after 2pm.
6. Using the information in problem 5, how many bacteria were there at 7pm that day?
7. Kaplan Corporation bought a computer for $1500. It is expected to depreciate at a rate of 22% per year. What will the value of the computer be in 2 years?
8. Radioactive iodine is used to determine the health of the thyroid gland. It decays according to the equation y = ae0.0856t, where t is in days. Find the halflife of this substance.
9. An anthropologist finds there is so little remaining Carbon14 in a prehistoric bone that instruments cannot measure it. This means that there is less than 0.5% of the amount of Carbon14 the bones would have contained when the person was alive. How long ago did the person die?
10. The Mendes family bought a new house 10 years ago for $120,000. The house is now worth $191,000. Assuming a steady rate of growth, what was the yearly rate of appreciation?

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