Edexcel Mathematics June 2018 · Paper 2 · Question 10 · ExamRizz

ExamRizzEdexcel MathematicsMathematics

June 2018 · Paper 2 · Question 10 · 8 marks

10. A spherical mint of radius 5 mm is placed in the mouth and sucked. Four minutes later, the radius of the mint is 3 mm. In a simple model, the rate of decrease of the radius of the mint is inversely proportional to the square of the radius. Using this model and all the information given, (a) find an equation linking the radius of the mint and the time. (You should define the variables that you use.) (5) (b) Hence find the total time taken for the mint to completely dissolve. Give your answer in minutes and seconds to the nearest second. (2) (c) Suggest a limitation of the model. (1) 27 28 29