Correct Answer - Option 4 : 11 h32m 39s AM

**Concept:**

There are 24 hours per day, so in one hour the earth rotates 1/24th of the way around 360 degrees divided by 24 gives an angle measure of 15 degrees per hour of time or **4 degree in one minute.**

Longitude line measurements start with the north-to-south line that goes through Greenwich which is 0 degree longitude or prime meridian, and measure in **positive numbers to 180 degrees eastward** and measures from Greenwich in the **negative direction to 180 degrees to westward**.

**Local time = GMT ± Longitude **

**(Take minus sign if longitude is westward and take positive sign if it is eastward)**

**Calculation:**

Local mean time = 8h 42m 15s.

1 minute = 4^{° }

Longitude of 42°36 W which is equivalent to 42 × 4 + 36× 4/60 = 170.4 minutes or 2 h 50 m 24 s

Now

8h 42m 15s = GMT - 2 h 50 m 24 s

**∴ GMT = 10 h 92m 39 s or 11 h 32 m 39 s AM**