Henry Ernest Dudeney/Puzzles and Curious Problems/63 - Westminster Clock/Solution

Puzzles and Curious Problems by Henry Ernest Dudeney: $63$

Westminster Clock

A man crossed over Westminster Bridge one morning between eight and nine o'clock by the tower clock

(often mistakenly called Big Ben, which is the name of the large bell only. But this is by the way).

On his return between four and five o'clock he noticed that the hands were exactly reversed.

What were the exact times he made the crossings?

Solution

He travelled out at $08 : 23 \tfrac {71} {143}$ and returned at $04 : 41 \tfrac {137} {143}$.

Proof

See Ambiguous Times for a full analysis.

$\blacksquare$

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Solutions: $63$. -- Westminster Clock
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $55$. Westminster Clock