Ms shah grades 3402 math problems during 5th period this is 54% of the total number of problems she need to grade what is the total number of problems she needs to grade

After 3 hours there is left 22.5 grams of radioactive material.

Step-by-step explanation:

We can calculate the mass of radioactive material remaining after 3 hours, by using the decay equation:           

    (1)

Where:

: is the initial mass = 180 g

: is the remaining mass after time t

λ: is the decay constant

The decay constant is given by:

Where = 1 h.

By entering λ into equation (1) we hve:

Therefore, after 3 hours there is left 22.5 grams of radioactive material.

I hope it helps you!