SOLUTION: A sample of radioactive substance decayed according to y=100(10)^-0.4x where y was the mass in grams and x was the time in hours after the original measurement. (a) How much was

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Question 890324: A sample of radioactive substance decayed according to y=100(10)^-0.4x
where y was the mass in grams and x was the time in hours after the original measurement.
(a) How much was present at the original measurement? (Hint: Let x=0.)
(b) How much was in the sample to the nearest gram after 3 hours?
(c] How much was present to the nearest gram after 5 hours?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
The formula should really be y=100%2810%29%5E%28-0.4x%29

Just substitute the given values of x to answer (a), (b), and (c).
Table of common logarithms or scientific calculator are the tools to use

Using (b) as example, y=100%2A10%5E%28-0.4%2A3%29
y=100%2A10%5E%28-1.2%29
y=100%2A6.303%2A%2810%5E%28-2%29%29
y=6.3