Use this plot to study exponentials a bit. Use the "Data Tips" tool under the Tools tab at the top of the figure panel $($This may be called the "Cursor Tool" in older versions of MATLAB$).$ You can now click on the curve and move along it $($using the arrow keys$)$ to read $x$ and $y$ values $-$ this is very handy. Figure out the half$-$life $($i$.$e$.,$ the time it takes for the concentration to fall to half of its initial value$).$ Use this half$-$life to calculate $.$ Use the rate constant to calculate $.$ Do these numbers agree?

$2.$ Use the cursor tool in MATLAB to find the percent concentration remaining after $1$ time constant. What is the concentration after $3-$time constants? $5$time constants? People often use $3-$time constants as a general rule for $95\%$ completion and $5-$time constants for $99\%$ completion. Do you see why?