Math. 69.107GH

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1. The rate at which bacteria multiply is proportional to the instantaneous amount present at any time. If the original number doubles in two hours, in how many hours will it triple??

2.5 hours

3.17 hours

none of these

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2. Radium decays at a rate, N(t), proportional to the instantaneous amount present at any time. If the half-life of radium is T years, determine the amount present after "t" years.

N(0)*(0.5)^(t/T)

N(0)* e^(t/T)

N(t)

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3. Find the half-life of a radioactive substance if three-quarters of it is present after 8 hours.

12.14 hours

19.27 hours

This cannot be found, not enough data is given.

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4. After two days, 10 grams of a radioactive chemical is present. Three days later there is only 5 grams left. How much of the chemical was present "initially" ?? (Assume a Law of exponential decay)

21.54 grams

18.67 grams

Not enough data is given

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