In general please round to one decimal place But think logic

In general, please round to one decimal place. But think logically if it is a number of insects, you cannot have half of an insect. The half-life of a radioactive substance is 2,500 years. If 20 grams are present now, how much will be present in 50 years? (Round your answer to two decimal places.)

Solution

The formula for half life is as under:

N(t) = N₀ (1/2)^t/t_1/2

Here, N_o = 20gms, t = 50 years. t_1/2 = 2500. Therefore, N(t) = 20 (1/2)^50/2500 = 20(1/2)^1/50 = 20( 0.5)^0.02

Or, N(t) = 20(0.986232704) = 19.72465409 = 19.7 gms ( on rounding off to 1 decimal place)