the mass of a radioactive substance follows a continuous exponential decay model, with a decay rate parameter of 9% per day. A sample of this radioactive substance had a initial mass of 4.42kg Find the mass of the sample after six days. round your answer is to two decimal places

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.