I have 2 problems that i have worked out, but i would like to know if i worked them correctly.

Problem 1.) Initially, 100 milligrams of a radioactive substance was present. After 6 hours, the mass decreased by 3%. If the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours.

For this problem i calculated that after 24 hours there will be 88.529g present.

Is this Correct?

Problem 2.) A small metal bar, whose initial temperature was 20 degrees C, is dropped into a large container of boiling water (100 degrees C). How long will it take or the bar to reach 90 degrees C if it is known that after 1 second the temperature increased by 2 degrees C?

For this problem I calculated that it will take 82.1335 seconds for the bar to reach 90 degrees C.

Is this Correct?

Thank You,

Diggidy