Question

When the time is 2.00 pm at \(30^\circ\) East Longitude, what is the time at \(20^\circ\) West Longitude?

• A. 10.40 am
• B. 5.20 pm
• C. 10.20 am
• D. 5.40 pm

Hint:

Remember: \[ \boxed{1^\circ=4\text{ minutes}} \] East $\rightarrow$ Time increases. West $\rightarrow$ Time decreases.

Answer 1

The Correct Option is A

Concept: \[ \boxed{1^\circ\text{ longitude}=4\text{ minutes}} \] Time increases towards the east and decreases towards the west.

Step 1: Find the longitude difference.
\[ 30^\circ E \text{ to } 20^\circ W =30^\circ+20^\circ =50^\circ. \]

Step 2: Convert longitude difference into time.
\[ 50\times4=200\text{ minutes} =3\text{ hours }20\text{ minutes}. \]

Step 3: Calculate the required time.
Since \(20^\circ\) W lies west of \(30^\circ\) E, its local time is earlier. \[ 2{:}00\text{ pm}-3\text{ h }20\text{ min} =10{:}40\text{ am}. \]

Step 4: Final conclusion.
Hence, the required time is \[ \boxed{10.40\text{ am}.} \]