Acertain medication is eliminated from the bloodstream at a rate of about 12% per hour. the medication reaches a peak level in the bloodstream of 40 milligrams. predict the amount, to the nearest tenth of a milligram, of the medication remaining 2 hours after the peak level and 3 hours after the peak level.

Let the current speed be "c";

Then the boat speed in still wate is "5c":

Upstream speed:

distance = 12 miles ; rate = 5c-c = 4c mph ; time = 12/4c = 3/c hrs

Downstream speed:

distance = 12 miles ; rate = 5c+c = 6c mph ; time = 12/6c = 2/c hrs

Step-by-step explanation:

Equation:

time + time = 2 1/2 hrs

3/c + 2/c = 5/2

Multiply thru by 2c to get:

6 + 4 = 5c

c = 2 mph (speed of the current)

5c = 10 mph (speed of the boat in still water)