Question

-09

2 1 point
The amount of a radioactive substance y that remains after t years is given by the equation y = a (e)^kt, where a is the initial
amount present and k is the decay constant for the radioactive substance. If a = 100, y = 50, and k = -0.035, find t.

Answer 1

19.80

Explanation:

Given the equation :

y = a (e)^kt

If a = 100, y = 50, and k = -0.035, find t.

50 = 100(e)^(-0.035t)

50/100 = e^(-0.035t)

0.5 = e^-0.035t

Take the In

In(0.5) = - 0.035t

-0.693147 = - 0.035t

-0.693147 / - 0.035 = t

19.8042 = t

Hence, t = 19.80