Aptitude - Clock - Discussion
Discussion Forum : Clock - General Questions (Q.No. 7)
7.
At what time between 5.30 and 6 will the hands of a clock be at right angles?
Answer: Option
Explanation:
At 5 o'clock, the hands are 25 min. spaces apart.
To be at right angles and that too between 5.30 and 6, the minute hand has to gain (25 + 15) = 40 min. spaces.
55 min. spaces are gained in 60 min.
| 40 min. spaces are gained in |  |
60 | x 40 |  min |
= | 43 | 7 | min. |
| 55 | 11 |
 Required time = 43 |
7 | min. past 5. |
| 11 |
Discussion:
76 comments Page 3 of 8.
Prashanth said:
10 years ago
If the minute hand is present before hour hand then use theta = 11/2min-30hr.
Like that hour hand is before minute hand theta = 30hr-11/2hr.
Use it you will get exact solution.
Like that hour hand is before minute hand theta = 30hr-11/2hr.
Use it you will get exact solution.
Tilak Dewangan said:
10 years ago
Sorry @Riddilavan your formula may wrong if you solve this question.
How many minutes after 7 o'clock and before 8'o clock will the hands of the clock be in opposite direction?
How many minutes after 7 o'clock and before 8'o clock will the hands of the clock be in opposite direction?
Shree said:
1 decade ago
Hey in some prob we are using theta=30h-11m/2 and here reddilavan has mentioned theta=11m/2-30h. How we knew in which prob which formula must be used na? Can any one explain me.
Swathi sayyapureddy said:
6 years ago
@Shree.
When hour hand is preceding minute hand then theta=30H~11M/2 will be used otherwise, means when min hand is preceding hour hand then theta=11M/2~30H can be used.
When hour hand is preceding minute hand then theta=30H~11M/2 will be used otherwise, means when min hand is preceding hour hand then theta=11M/2~30H can be used.
(4)
Akshi panwar said:
1 decade ago
15 minutes is added because perpendicular in clock is at 15 min.
After every 15 min gap between hour hand and min hand there will be a 90 degree angle is formed.
After every 15 min gap between hour hand and min hand there will be a 90 degree angle is formed.
Amit said:
1 decade ago
@Harry.
Both the formulas are correct.
1st one is used for finding the angle when hour is less than 6.
2nd one is used when the hour is more than 6.
Both the formulas are correct.
1st one is used for finding the angle when hour is less than 6.
2nd one is used when the hour is more than 6.
Harry said:
1 decade ago
@Reddilavan Can you please explain how to decide the exact formula
1) angle=(11/2)*min-30*hr
2) angle=30*hr-(11/2)*min
Which formula is correct ?
1) angle=(11/2)*min-30*hr
2) angle=30*hr-(11/2)*min
Which formula is correct ?
Appu said:
8 years ago
At 5:30, the hands are 55 mins apart.To get an angle 90 btw them space must 15 mins apart,
so, the space is 55-15=40.
therefore,60/55-40=43 7/11.
so, the space is 55-15=40.
therefore,60/55-40=43 7/11.
(2)
Shubham said:
1 decade ago
Can any one let me know that the angle which we always consider is in clockwise direction or we can consider that in anticlockwise direction too.
Ash said:
3 years ago
@All.
My doubt is here the question is between 5:30 & 6.
So, for 90degress it's should be 5:45 right? Why did they assume from 5'o clock?
My doubt is here the question is between 5:30 & 6.
So, for 90degress it's should be 5:45 right? Why did they assume from 5'o clock?
(31)
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