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1 Unit 1: Pure Mathematics A

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Question 358

The decay of a radioactive substance is modelled using the formula N=1000e−ktN = 1000e^{-kt}N=1000e−kt where N N\,N is the number of atoms after t t\,t years and k k\,k is a positive constant.

a.

Write down the number of atoms when the substance started to decay.

[1]
b.

Given that it takes 14.4 years for half of the substance to decay, find the value of k k\,k to 3 significant figures.

[4]
c.

Calculate the number of atoms left when t=30t = 30t=30.

[1]
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1 Unit 1: Pure Mathematics A Questions

  1. A Level
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