Question 9 A radioactive substance decays at a continuous rate of $14.9 \%$ per day. After 8 days, what amount of th substance will be left if you started with $300 \mathrm{mg}$ ? (a) First write the rate of decav in derimal form. $r=$ (b) Now calculate the remaining amount of the substance. Round your answer to two decimal places. Question Help: @Messageinstuigar: ? Next,Question

Step 1 ：First, we need to convert the decay rate from percentage to decimal form. The decay rate is given as 14.9%, so in decimal form it is \(-0.149\).

Step 2 ：Next, we use the exponential decay formula, which is \(A = P * e^{rt}\), where \(A\) is the amount of substance after time \(t\), \(P\) is the initial amount of substance, \(r\) is the decay rate, and \(t\) is the time.

Step 3 ：In this case, \(P = 300\) mg, \(r = -0.149\), and \(t = 8\) days.

Step 4 ：Substituting these values into the formula, we get \(A = 300 * e^{-0.149 * 8}\).

Step 5 ：Calculating this gives us \(A = 91.08402887270195\) mg.

Step 6 ：Rounding this to two decimal places, we get \(A = 91.08\) mg.

Step 7 ：So, the remaining amount of the substance after 8 days is approximately \(\boxed{91.08 \, \text{mg}}\).