Train Station Riddle
A train leaves London at 10:15 AM, traveling at an average speed of 60 km/h. Another train leaves from the same station 45 minutes later, traveling on the same track at 90 km/h.
A box of biscuits
A box of biscuits contains 36 biscuits. 20 biscuits have foil wrappers. 15 are chocolate biscuits with foil wrappers. If 9 are not chocolate and do not have a foil wrapper, then how many chocolate biscuits are there?
Step 1: Distance Covered by the First Train Before the Second Train Starts
ReplyDeleteBy the time the second train departs at 11:00 AM, the first train has already been traveling for 45 minutes (or 0.75 hours).
Distance traveled by the first train:
Distance = Speed × Time
= 60 × 0.75
= 45 km
So, the first train is 45 km ahead when the second train starts at 11:00 AM.
Step 2: Relative Speed
Since both trains are moving in the same direction, the relative speed is:
90 km/h - 60 km/h = 30 km/h
Step 3: Time Taken to Catch Up
Time required to close the 45 km gap:
Time = Distance ÷ Relative Speed
= 45 ÷ 30
= 1.5 hours
Step 4: Find the Catch-Up Time
The second train started at 11:00 AM, so adding 1.5 hours:
11:00 AM + 1 hour 30 minutes = 12:30 PM
Answer:
The second train will catch up with the first train at 12:30 PM.