Higher June 2017 Paper 4 Q10

OCRHigherCurrent spec6 marksPercentages

10 On 1st November 2015 there were 4200 trees planted in a wood.
On 1st November 2016, only 3948 of these trees were still alive.

It is assumed that the number of trees still alive is given by

\[N = ar^t\]

where \(N\) is the number of trees still alive \(t\) years after 1st November 2015.

(a) Write down the value of \(a\). [1]
(b) Show that \(r\) is 0.94. [2]
(c) Show that on 1st November 2030 the number of trees still alive is predicted to have decreased by over 60% compared with 1st November 2015. [3]
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