how much will remain after 56 days?

Question

the half-life of chromium-51 is 28 days. If the sample originally starts with 510 grams

Answer 1

t = number of days elapsed = 56

m₀ = initial amount = 510 g

m(t) = amount remaining after t days

m(t) = m₀ (0.5)^t/28

You have values for m₀ and t. Plug them into the equation and get m(t). You will be left with 1/4 of the initial amount.