It's your turn on growth and decay problems

Do your best in trying to solve the following problems. In any case some of them are solved in the video and all of them are solved in the pdf file below.

Exercise 1.

A capital of 8 000 pounds is invested with a given annual compound interest of (5%). How many years and months does it take to reach 10 000 pounds? Express the result in decimal form (ex: 6.87)

Exercise 2.

The mass of the Polonium, a radioactive substance, is expressed at time (t) by the formula [m(t)=m_02^{-t/140},] where (m_0) is the initial mass. How many days does it take to decay to half its original mass?