Mathematics (AS & A Level) · May / June 2017 · Paper 32 · Question 5

In a certain chemical process a substance A reacts with and reduces a substance B. The masses of A and B at time t after the start of the process are x and y respectively. It is given that dy dt = −0.2xy and x = 10 1 + t 2 . At the beginning of the process y = 100.

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