Ascientist begins with 250 grams of a radioactive substance. after 250 minutes, the sample has decayed to 36 grams. write an exponential equation f(t) representing this situation. (let f be the amount of radioactive substance in grams and t be the time in minutes.)

f(t) = 250

Step-by-step explanation:

Let f(t) =

where f is the amount of radioactive substance in grams

and t is the time in minutes

initially (at t=0), f = 250 grams

⇒f(0) = 250 grams

⇒ = 250

⇒ = 250

⇒ = 250 grams {∵}

⇒f(t) = 250

At t = 250 minutes, f = 36 grams

⇒f(250) = 36 grams

⇒250 = 36

⇒ = = 0.144

⇒250 = ㏑ 0.144 = -1.938

⇒ = - = -0.007752

∴f(t) = 250