Question

The local mean time at a place located in longitude ${90}^{\circ }{40}^{\prime }E$ when the standard time is 6 h 30 min and the standard meridian is ${82}^{\circ }{30}^{\prime }E$ is

• A. 7 h 2 min 40 s
• B. 5 h 2 min 40 s
• C. 5 h 57 min 20 s
• D. 6 h 30 min

Answer 1

The correct option is A 7 h 2 min 40 s

Difference between longitude of local place and standard meridian,
$={90}^{\circ }{40}^{\prime }E-{82}^{\circ }{30}^{\prime }E=8^{\circ }{10}^{\prime }$

As we move towards east from standard meridian, there is gain in time.
We know,
$\because 1^{\circ }=4min$
$\therefore 8^{\circ }{10}^{\prime }=32min40s$

So local time,
$=6h30min+32min40s$
$=7h2min40s$