Henry Ernest Dudeney/Puzzles and Curious Problems/12 - Reductions in Price/Solution

by : $12$

 * Reductions in Price

Solution

 * $\pounds 78 \tfrac 1 8$, or $\pounds 78, 2 \shillings 6 \oldpence$

Proof
The numbers:
 * $512, 320, 200, 125$ form a geometric sequence whose common ratio is $\dfrac 5 8$.

Hence the next reduction is expected to be $125 \times \dfrac 5 8 = \dfrac {625} 8 = 78 \tfrac 1 8$.