3. There are 120000 red squirrels living in Scotland. This represents $75 \%$ of their total UK population. How many more red squirrels live in Scotland than live in the remainder of the UK?
A 30000
B 40000
C 60000
D 80000
E 90000
3. D First note that three quarters of the UK red squirrels live in Scotland. So one quarter of the UK red squirrels live in the remainder of the UK and the number of such squirrels is therefore one third of the number of red squirrels living in Scotland, which is $\frac{1}{3} \times 120000=40000$.
So the required difference equals $120000-40000=80000$.