Aptitude - Clock - Discussion

How is the angle traced by hours hand is 125/12?

But 30*9-11/2*0 = 270 why please explain the angle between hands at 9.00 am.

Correct formula is 30h - 11/2m. So this mean at 0 hours and 1 minute you get an angle of: 30*0 - 11 / 2*1 = -5.5 ?

How come the minute arrow moves almost 6 degrees then?

We can easily solve this sum.

The hour hand covers 1/2 Degree per minute means for 25 minutes 25/2= 12/2 means 30-12 1/2= 17 1/2 Degrees.

1 Hour hand 6 hours = 180 degrees.

180 + 17.5 = 197.5.

The formula is 6m-(30h+m/2) m=minutes h=hour.
For example 11:26.

6(26)-(30(11)+(26)/2).
156-(330+13).
156-343.
-187.

If you get a result that is negative, all it means is that the hour hand is ahead of the minute hand, simply multiply the answer by -1 and then subtract that from 360.

Reflex angle = 360-(angle between).

Angle between = (30*hour)-((11*minute)/2).
= (30*10)-((11*25)/2).
= (300-137(1/2)).
= 162 (1/2).

Reflex angle = 360-(162 (1/2)).
= 197 (1/2).

Reflex angle = 360-(angle between hours hand and minute hand).

/*10.25 it can be written as in hrs.*/

Total hours = (10+25/60) = (10+5/12) = (125/12).

Angle traced by hours hand = (125/12)*(360/12) = 312(1/2).

Angle traced by minutes hand = 25*(360/60) = 150.

Angle between 2 hands = 312(1/2)-150 = 162(1/2).

/*The angle formed by a both hands and a perpendicular to the surface at the point of reflection.

Here the surface is circular so ref angle is 360.
*/

Reflection angle = 360-(Angle between 2 hands).

= 360-162(1/2).

= 197(1/2).

Please not that 10.25 cannot be taken as 25 minutes past 10. Rather, it should be 15 mins past 10. Its basic maths.

This table show the movement angle of each hand in each time in a clock.

TIME   Hour   Min   Sec

1 hour   30°   360°   21600°
1 Minute   0.5°   6°   360°
1 Second   1/120°   0.1°   6°

Take simple solution,

After every 12 minutes, Hour clock will move 1 step.
=25 minutes = almost 2 steps moved hour sign from 10 to 10.02.

Now difference between hour & minute clock is 25+8=33 step

1 step = 6 degree than 33 x 6 = 198, answer option near to 198 is given 197 1/2 which is correct.