solve please i need help

Question

A radioactive substance decays exponentially. A scientist begins with 100 milligrams of a radioactive substance. After 34 hours, 50 mg of the substance remains. How many milligrams will remain after 52 hours?

Answer 1

1/2 = e^34r

ln.5 = 34r

r = ln.5/34 = .020387 = 2.04% decay rate

x = 100e^.020387(52)

= 34.64 mg after 52 years