Debasing the Coinage
How much lighter will £5 worth of 5p's be with these new lighter coins?
Age
11 to 14
Challenge level
In 1990 a new size 5p coin was minted. The old size weighed 5.65g while the new size weighs 3.25g.
How much lighter will your pocket be if it contains £5 worth of the new size coins instead of the old size?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
Answer: 240g
There are 100 5p's in £5.
The old coins weighed $100 \times 5.65 = 565$g, while the new coins weigh $100 \times 3.25 = 325$g.
So your pocket is $565-325=240$g lighter.