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Aptitude - Clock - Discussion

Discussion Forum : Clock - General Questions (Q.No. 7)
Clock
7.
At what time between 5.30 and 6 will the hands of a clock be at right angles?
43 5 min. past 5
11
43 7 min. past 5
11
40 min. past 5
45 min. past 5
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 8 of 8.
Margaret said:   1 decade ago
If we consider the basic solution, and start at 5:30 then min. space between hands at that time is 5 spaces and we need 10 more spaces to get right angle.

So simply (60*10)/55 min past 5:30 i.e. 30 min.+(60*10)/55 min. past 5.

What is wrong in the solution?
Chan said:   1 decade ago
@Amit.

If the hour is equal to 6, then what is the formula for that.

Is it the angle 180 for straight angle and 90 for right angle.
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.
Pavansairam said:   1 decade ago
If theta = 90 and you go for 1st(b/w 5.30 to 6.00 etc problems).

If theta = 180 you go for 2nd.
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.
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 ?
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