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:
48 comments Page 1 of 5.
Sakshi said:
1 decade ago
How do we know that min? Hand has to gain 45 mins?
Yamini said:
1 decade ago
Why you take the 55 min spaces ?
Krish said:
1 decade ago
Sakshi,
The question is between 9 and 10 both the hands must coincide,.
So for the minute hand to reach 9 it has to gain 45 minute spaces.
The question is between 9 and 10 both the hands must coincide,.
So for the minute hand to reach 9 it has to gain 45 minute spaces.
Vipin said:
1 decade ago
Alternative method::
Let the minutes covered when d situation occurs = x
now,
(total degrees covered by minute hand) - (total degrees covered by hr hand)= (outer angle between 12 and 9) i.e.
6x - x/2 = 270
x=540/11 which is our ans. :)
Let the minutes covered when d situation occurs = x
now,
(total degrees covered by minute hand) - (total degrees covered by hr hand)= (outer angle between 12 and 9) i.e.
6x - x/2 = 270
x=540/11 which is our ans. :)
Manish said:
1 decade ago
I don't understand this method please explain it. Why we take 55 min ?
Shree Hema said:
1 decade ago
@manish
better use this formula
theta=11(m)/2-30(h)
if both hands coincide degree ll be 0
if both hands r in opposite direction degree will be 180
if both hands r in right angle degree will be 90
here it coincides so 0 degree
we have to find min only so keep that parameter(m) as it is, use minimum hour for hour parameter(h=9)
0=11(m)/2-30(9)
m=49 1/11
Got It???
better use this formula
theta=11(m)/2-30(h)
if both hands coincide degree ll be 0
if both hands r in opposite direction degree will be 180
if both hands r in right angle degree will be 90
here it coincides so 0 degree
we have to find min only so keep that parameter(m) as it is, use minimum hour for hour parameter(h=9)
0=11(m)/2-30(9)
m=49 1/11
Got It???
Krishnadas said:
1 decade ago
@sree. Good work. But is this formula standard?
Avijeetkumar said:
1 decade ago
@shree. You are right.
Senthamizh said:
1 decade ago
@Shree: is that standard formula???
Anil said:
1 decade ago
If time is between x and y:
[x*5+angle]*(12/11) past x.
[x*5+angle]*(12/11) past x.
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