Question

A watch was slow by 5 minutes at 4 p.m. on Wednesday, but it was fast by 10 minutes at 4 p.m on Saturday. At what time did it show the right time?

• A. 4 p.m. on Thursday
• B. 4m. on Friday
• C. 12 Noon on Thursday
• D. 4 p.m. on Friday
• E. 12 Noon on Friday

Answer 1

The Correct Option is A

Step 1: Understand the problem.
A watch was slow by 5 minutes at 4 p.m. on Wednesday and fast by 10 minutes at 4 p.m. on Saturday. We need to determine the time when the watch showed the correct time.

Step 2: Calculate the time difference between Wednesday and Saturday.
The time from 4 p.m. on Wednesday to 4 p.m. on Saturday is 48 hours (2 full days).

Step 3: Determine the total time gained or lost.
The watch was slow by 5 minutes at 4 p.m. on Wednesday and fast by 10 minutes at 4 p.m. on Saturday. The net change in time is:
\( \text{Net change} = 10 \, \text{minutes (fast)} - 5 \, \text{minutes (slow)} = 15 \, \text{minutes (gained)} \)

Step 4: Calculate the rate at which the watch gains time.
The watch gained 15 minutes over 48 hours. Therefore, the rate at which the watch gains time is:
\( \text{Rate} = \frac{15 \, \text{minutes}}{48 \, \text{hours}} = \frac{5}{16} \, \text{minutes per hour} \)

Step 5: Find the time when the watch showed the correct time.
Since the watch gains time, we can calculate the time at which the watch was correct by subtracting the time gained from 4 p.m. on Wednesday. The watch gained 5 minutes every 16 minutes, so we calculate the time when the watch would have been correct.

Final Answer:
The correct time was at 4 p.m. on Thursday.

The correct option is (A): 4 p.m. on Thursday.