NEED HELP ASAP A medication has a half-life of 4 hours after it enters the bloodstream. A nurse administers a dose of 500 milligrams to a patient at noon.

Only answer if you know pls!!

Find the amount of medication, in milligrams (mg), remaining in the patient's body at: (Round to the nearest 10th)

a. 3 p. m. on the same day:

b. 8 p. m. on the same day:

2. The expression 500 x (1/2)^5/4 represents the amount of medicine in the body sometime after it is administered. What is that time? (Make sure to signify am or pm)