Aptitude - Clock - Discussion

@Manab.

Can you explain me? How was the formula formed?

Yes, it is very simple with formula, everyone can do it.

1 hr = 60 min.

8 hr = 60*8 = 480.

30 min = 480+30 = 510 hr.

Angle traced by hour hand = 510 hr/2 = 255.

Angle traced by min hand = 360/60*30 = 180.

= 255-180 = 75.

Formula for 30(h-m/5)+m/2?

If the time is 1.5 then what is the angle between hour hand and minute hand?

Guys to solve the angle between the hour hand and the min hand :

For Ex:

Let the time be 8:30 so that the hour hand is slightly far from 8 and the min hand points exactly on 6. Then the degrees between two no. S is 30 degrees (hour hand).

Now, the angle between hour hand (approximately at 8) and at 6 (min hand) is 60 degrees. Now consider only the min hand (on 6).

Now do k*30 (30 because the min hand is at 6 and k is a constant having a value of 0.5). Therefore it becomes 30*0.5 gives 15 degrees. Add these 15 degrees to 60 degrees which we got earlier. Therefore it become 60+15 = 75 degrees.

Explanation is big but am sure I will understand.

Clock is divided into 60 equal minute division.

1 minute division = 360/60 = 6 degree. So for 8:30.

Minute hand is on 6 while hr hand is in middle of 8 and 9.

6-7 = 5min = 5*6 = 30 degree.

7-8 = 30min.

8-8.5 = 15 min.

Total angle = 6-7+7-8+8-8.5.

= 30+30+15.

= 75 degree.

Using formula is quite easy method friends.

Look at the clock -_- it simply can't be 75 deg it has to be 60deg.
Since 6-9 is 90deg.

And can be divided in 3 intervals.
i.e. 6-7 , 7-8, 8-9.

So obviously u divide 90 by 3 ie. 30deg each.
So when its 8:30.

Hour hand on 8.
Minute hand on 6.

So it covers 2 intervals of 30deg.
HENCE 60 degree

Why (11/2) *min-30* hrs is not working in 4:40?