On 1st November 2015 there were 4200 trees planted in a wood - OCR - GCSE Maths - Question 10 - 2017 - Paper 1

To find $r$, we consider the number of trees alive after one year. According to the given information, on 1st November 2016, 3948 trees were still alive. We can set up the equation:

$N = ar^t$

Substituting the known values:

$3948 = 4200 imes r^1$

Solving for $r$, we have:

$r = \frac{3948}{4200} = 0.94$

To find the number of trees still alive on 1st November 2030, we calculate the time $t$:

$t = 2030 - 2015 = 15$

Using the formula:

$N = 4200 imes (0.94)^{15}$

Calculating this value:

$N \approx 4200 \times 0.3965 \approx 1660.22$

To determine the percentage decrease, we can find:

$\text{Percentage Decrease} = \frac{4200 - 1660.22}{4200} \times 100\% \approx 60.4\%$

Since this is over 60%, we can conclude the claim.