NIMCET 2008 — Reasoning PYQ
NIMCET | Reasoning | 2008A watch which gains 10 s in 5 min was set correct at 9 am when the watch indicated 20 min past 7 O’ clock, the same evening, the true time is
Choose the correct answer:
- A.
7 pm
(Correct Answer) - B.
7 : 40 pm
- C.
7 : 10 pm
- D.
8 pm
7 pm
Explanation
1. Calculate the Error Rate
The watch gains 10 seconds every 5 minutes.
First, let's find the total "watch time" that passes for every 5 minutes of "true time":
-
True Time interval = 5 min
-
Watch Time interval = 5 min+10 sec
To make the units consistent:
So, 631 minutes of the Watch Time is equal to 5 minutes of the True Time.
2. Find the Total Watch Time Elapsed
The watch was set correct at 9 am.
The watch now shows 7:20 pm (20 min past 7) the same evening.
-
Time from 9 am to 12 pm = 3 hours
-
Time from 12 pm to 7:20 pm = 7 hours 20 minutes
-
Total Watch Time = 10 hours 20 minutes
Convert this total into minutes:
3. Calculate the True Time Elapsed
We use the ratio derived in step 1:
Substituting the values:
Now, simplify:
4. Determine the Actual Time
Convert the 600 minutes of True Time back into hours:
The true time is exactly 10 hours after 9 am.
-
9 am+10 hours=7 pm
Final Answer
The true time is 7 pm.
The correct option is (a).
