Machine-translated by Google. Questions are authored in English.
Top

Discussion

How much does a watch lose per day, if its hands coincide ever 64 minutes?

  • A.32 8/11
  • B.33 8/11
  • C.34 8/11
  • D.35 8/11

Answer: A

In a correct clock the hands coincide every

\[ \frac{720}{11} = 65\tfrac{5}{11} \text{ minutes} \]

Here they take 64 minutes, less than they should, so the watch is running fast - but the question asks how much it loses, and the conventional treatment measures the shortfall of the interval:

\[ \frac{720}{11} - 64 = \frac{16}{11} \text{ minutes per interval} \]

\[ \frac{16}{11} \times \frac{1440}{64} = \frac{23040}{704} = 32\tfrac{8}{11} \text{ minutes a day} \]

The 24-hour figure comes from the number of coincidence intervals in a day, \( \tfrac{1440}{64} = 22.5 \).

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.