Aptitude - Clock - Discussion

Discussion Forum : Clock - General Questions (Q.No. 8)
8.
The angle between the minute hand and the hour hand of a clock when the time is 4.20, is:
10°
20°
Answer: Option
Explanation:

Angle traced by hour hand in 13 hrs = 360 x 13 ° = 130°.
3 12 3

Angle traced by min. hand in 20 min. = 360 x 20 ° = 120°.
60

Required angle = (130 - 120)° = 10°.

Discussion:
79 comments Page 1 of 8.

Javed said:   10 years ago
So simple guys.

Total 360 degrees.
Total clock = 12 hours.
360/12 = 30 degrees.

That is 1 hour = 30 degrees.

1 minute = 360/60 = 6 degrees.
1 min = 6 degree.
1*20 = 6*20.
20 min = 120 degrees -----> 1st equation.

Simplify:

= 4 (1/3) (i.e 4 hr and 20 min).

=> 4*3+1/3.
=12+1/3.
= 13/3.

= (13/3)*(360/12).
= (13/3)*30 {cancel 3*10 = 30}.

13*10 = 130 ------> 2nd equation.

Remove 1st equation and 2nd equation.

130-120 = 10 degrees.

Answer is 10 degrees.

Hemant said:   1 decade ago
We can also mark the ans by common sense..ie,

1. It is clear that the angle could not be 0.

2. Since the hour hand leads the min hand, and it will be in between 4 to 5, if the time will be 4.30, hour hand exactly in mid of 4 n 5, i.e 5min=30 degree, than half is 15 degree if the time would 4.30, but it is less than the 4.30, so angle will be slightly less than the 15 degree.

RAHUL R. PARSODKAR said:   8 years ago
SIMPLE FORMULA.

30*H - (11/2)*M
Where, 'H' FOR 'HOUR'; 'M' FOR 'MINUTE'.
Answer will generated in degree angle.

Note:- Suppose, answer of angle is greater than 180 degrees then answer will be reduced or minus (- 360) from original angle for example
1) 3:40 hr.

According to formula,
30*3 - (11/2)*40.
= 90-220
= -130
= 130 degree (and take it +Ve).

Omkar said:   4 years ago
Short trick for these ans.

Take a ratio of 4.20=1:5 then there is a formula, when ur ratio is 1:5 then, divide minutes by 2
i.e 20÷2 = 10.

Also when ratio is 1:8 then (minute-hours) * 2
Also for the ratio 1:3, = minute * 4+minute ÷2
Ratio 1:10, θ = minute*2.5.
1:4then θ= minute*2.
1:6 θ = minute ÷2.
(1)

Tejkishor said:   1 decade ago
@Saum

We take 12 O'clock point as reference point (r.p).

So we subtract the angle move by hr hand from the r.p. and the angle move by the min hand from the same to get the separating angle between them
and also at 4:20 the hands doesn't coincide in my watch.

Ali Zohair Shah said:   1 decade ago
It is 4 degree.
Because hour hand moves 30 degree in 1hour.

So it is 1/3 hours passed so it rotates 10 degree.
Total angle of hours hand is 30*4+10 = 130 degree.

Minute hand moves 6 degree in 1 minute = 20*6 = 120 degree.
So 130-120 = 10 degree.

Saum said:   1 decade ago
Why we are substracting angle traced by hour hand and angle traced by minute hand ?

One another thing is that - if we see the clock at 4.20 hour hand is at 4 and minute hand is also at 4. So angle between them must be 0 degree.

Please clear me.

Nikhila said:   1 decade ago
Hey all.

We know that the minute hand is at 4 at 4. 20. We jst hav to calculate the angle moved by hour hand from 4 for 20 min.

For 60 min, Hour hand covers 360/12=30 degree.

For 20min, it covers 30*20/60= 10 degree. (Just cross multiply. ).

SIVAKRISHNA said:   7 years ago
@Anil

|11M-60H|/2 formula. This formula is not sufficient for some problems.

For example; can you find an angle between the minute hand and hour hand of a clock when the time is 3:40?

Solution:

|11*40-60*3|/2.
=440-180/2.
=360/2.
=180°.

Junaid said:   10 years ago
Its so simple guys.

Total 360 degrees.
Total clock = 12 hours.

360/12 = 30 degrees.

Now 1 hour = 30 degrees.

1 hour = 60 minutes.
So 30/60 = 0.5 Degrees.

Now 1 minute = 0.5 Degrees.

Just multiply Degree*Minutes.

= 0.5*20 = 10 Degree.


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