The half-life of krypton-91 is 10 seconds. At time t = 0 a heavy canister contains 100 g of this radioactive gas. After how long will the amount of krypton-91 remaining be reduced to 1 microgram (1 microgram = 10−6 g). Round your answer to the nearest whole number. Hint: You'll need to use the function () = 0 −, where 0 is the initial mass of the radioactive substance, is the relative decay rate, and is the mass remaining at time . Round your decay rate, , to 6 decimal places. Then round the answer to the question to the nearest whole number.