Question

A train crosses Park Street every forty-five minutes. About 15 minutes ago, one train has crossed Park Street, and the next train will be crossing Park Street by 9.45 am. What is the time now?

• A. 8.45 am
• B. 9.00 am
• C. 9.15 am
• D. 9.30 am

Hint:

Calculate the "last train time" first, then add the elapsed time.

Answer 1

The Correct Option is C

Step 1: Note the fixed interval.
A train crosses Park Street every 45 minutes, so successive crossings are exactly 45 minutes apart.
Step 2: Anchor on the next crossing.
The next train will cross at 9:45 am.
Step 3: Find the previous crossing.
The crossing before 9:45 am happened 45 minutes earlier, at $9:45 - 0:45 = 9:00$ am.
Step 4: Use the 'about 15 minutes ago' clue.
A train crossed about 15 minutes ago, and that crossing was the 9:00 am one.
Step 5: Add 15 minutes to that crossing.
If 9:00 am was 15 minutes ago, then now is $9:00 + 0:15 = 9:15$ am.
Step 6: Cross-check the next train.
From 9:15 am the next crossing at 9:45 am is 30 minutes away, comfortably within the 45-minute cycle, so the timeline is consistent. The current time is 9:15 am, matching option 3.
\[ \boxed{9.15 \text{ am}} \]