# Aptitude - Clock - Discussion

Discussion Forum : Clock - General Questions (Q.No. 15)

15.

At what time between 9 and 10 o'clock will the hands of a watch be together?

Answer: Option

Explanation:

To be together between 9 and 10 o'clock, the minute hand has to gain 45 min. spaces.

55 min. spaces gained in 60 min.

45 min. spaces are gained in | 60 | x 45 | min or 49 | 1 | min. | |

55 | 11 |

The hands are together at 49 | 1 | min. past 9. |

11 |

Discussion:

46 comments Page 1 of 5.
Nikhil B said:
3 years ago

@All.

θ = (11m/2) - 30h is a standard formula.

θ = (11m/2) - 30h is a standard formula.

(2)

Vinayak said:
5 years ago

How does 60/55*45 become 49 1/11?

Please if anybody can explain this?

Please if anybody can explain this?

(1)

Akhilesh said:
7 years ago

My solution is:

Both the hands will meet somewhere between 9 and 10 i.e after the minute hand has reached 9 ( after 45 minutes). In these 45 mins the hour hand must also have traveled forward by some angle.

The angles covered by the hour hand in 45 mins will be 22.5. (how? in one min it covers 1/2 that's why!).

Now, let's suppose it takes another x mins for both of them to reach the point where they will coincide.

The angle traveled by hour hand will be x/2 and by the minute hand will be 6x.

Now in order to coincide with the hour hand, the minute hand has to cover the total angle the hour hand has moved forward.

So, 6x = x/2 + 22.5.

Both the hands will meet somewhere between 9 and 10 i.e after the minute hand has reached 9 ( after 45 minutes). In these 45 mins the hour hand must also have traveled forward by some angle.

The angles covered by the hour hand in 45 mins will be 22.5. (how? in one min it covers 1/2 that's why!).

Now, let's suppose it takes another x mins for both of them to reach the point where they will coincide.

The angle traveled by hour hand will be x/2 and by the minute hand will be 6x.

Now in order to coincide with the hour hand, the minute hand has to cover the total angle the hour hand has moved forward.

So, 6x = x/2 + 22.5.

Jeet said:
8 years ago

In Q6 at 7, they are 25 mins apart, but in this Q at 9 they are 45 mins apart, is the angle measured clockwise/ anti clockwise?

Aarthi said:
8 years ago

Can you tell me the correct explanation?

Abhishek said:
8 years ago

@Kapil.

Awesome man done in the most basic way manner as possible. Really appreciate your work.

Awesome man done in the most basic way manner as possible. Really appreciate your work.

Smita said:
8 years ago

Past 9n means?

Sonam said:
8 years ago

When asking will the hands of a watch be together?

Use (60/11)h.

= 60*9/11.

= 540/11.

= 49 1/11.

Use (60/11)h.

= 60*9/11.

= 540/11.

= 49 1/11.

Bhavesh Kirange said:
7 years ago

I don't understand the concept here you are assuming. In question from 9 to 10 o'clock the hands should be meet each other on 9.50 o'clock in real situation by watch.

But how could you say here they are meeting on 9.45 o'clock means we are suppose to assume hour hand at stable position?

But how could you say here they are meeting on 9.45 o'clock means we are suppose to assume hour hand at stable position?

Rohan said:
7 years ago

Let QH and QM be angular speed of hour and minute hand respectively.

QH = 360/720 = 0.5 (degree/minute) QM = 360/60 = 6 (degree/minute).

Relative angular speed (QM-QH) = 11/2 = 5.5.

Now at 9:45 angle between minute and hour hand will be = 22.5 deg.

Time taken for minute hand to coincide hour hand = 22.5/5.5 = 45/11.

= 45/11 = 4+1/11.

Hence time at which hour and minute hand coincide is:

Hour = 9 minute = 45+4+1/11 = 49+1/11 or 45 1/11 past 9.

QH = 360/720 = 0.5 (degree/minute) QM = 360/60 = 6 (degree/minute).

Relative angular speed (QM-QH) = 11/2 = 5.5.

Now at 9:45 angle between minute and hour hand will be = 22.5 deg.

Time taken for minute hand to coincide hour hand = 22.5/5.5 = 45/11.

= 45/11 = 4+1/11.

Hence time at which hour and minute hand coincide is:

Hour = 9 minute = 45+4+1/11 = 49+1/11 or 45 1/11 past 9.

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