To solve this problem, plug 8250 in for b and 15 in for t and then solve for k:

*Divide both sides by 1000*

*Take the natural log (ln) of both sides*
2.1102=15k
*Divide both sides by 15*
0.1406=k
0.1406 rounds to 0.141 which is close to a. 0.143.
Hope this helps!!