Aptitude - Clock - Discussion

Discussion :: Clock - General Questions (Q.No.12)

12. 

The angle between the minute hand and the hour hand of a clock when the time is 8.30, is:

[A]. 80°
[B]. 75°
[C]. 60°
[D]. 105°

Answer: Option B

Explanation:

Angle traced by hour hand in 17 hrs = 360 x 17 ° = 255°.
2 12 2

Angle traced by min. hand in 30 min. = 360 x 30 ° = 180°.
60

Required angle = (255 - 180)° = 75°.


Deep said: (Jun 12, 2010)  
How 17/2 came please anyone answer?

Prasad said: (Jun 21, 2010)  
17/2 = 8.5 but 8hr 30min, so how it's came 17/2 ?

Why we use this? can any one tell me please?

Sundar said: (Jun 21, 2010)  
Hi @ALL

We can write 8.30 as 17/2 hours.

Let me explain.

17/2 = 8.5 = 8 hours + 0.5 hours

= 8 hours + 1/2 hours

= 8 hours + 1/2 x 60 mins (.: 1 hour = 60 mins, Therefore, 1/2 hours = 30 mins)

= 8 hrs 30 min.

Therefore, we can write 8-hrs 30-min as 17/2.

While solving problems, make all numbers in vulgar fraction, it will be easy to solve problems quickly.

For example: 360/12 x 17/2 = ?

It is easy to solve. Have a nice day!

Shekhar Bhakat said: (Aug 26, 2011)  
Try this formula it can solve any tipe of clock related problem.

Angle b/w two handes of the clock= (11/2) *min-30*hr;.

Ndd said: (Sep 21, 2011)  
8hr+30/60=17/2.

Marati Raju said: (Oct 3, 2011)  
It is . . . . Very simple
by the Formula:
30H-[11/2]M
at 8.30
i.e 240-165=75degrees

I hope that every one understood this . . . . .

Nagmani Sinha said: (Dec 15, 2011)  
We can use other formula too...
30h-6m
where:
H=total hours including minute parts...
m=minutes

in above qn it would be

30*17/2-6*30=255-180=75;

Hope its easier formula.

Suresh said: (Apr 12, 2012)  
Hours hand should be calculated by considering
hours Hand -( 8 * 360/12)= 240 deg
Minutes Hand - ( 30 * 360/60) = 180 deg

Total angle b/w Hour and Min = 240 -180 = 60 deg.

This is Practically as per the clock system.

Naveen said: (May 26, 2012)  
Can we write 17/2 we also write this 34/4 that is also equals.

Shoubhick said: (Sep 17, 2012)  
Hey guys...
no need to apply any formula..
just look at any clock,each division(1/12) is 360/12=30 deg,and 1/24 division is 15 deg,so in 8:30--> 30+30+15=75 deg

Harshita Jain said: (Jul 6, 2013)  
8 hrs = 8*60 = 480 min.

8.30 = 480+30 = 510 min.

510 convert into hrs -> 510/60 = 17/2 hrs :).

Santoshkumar said: (Sep 1, 2013)  
Just do this:

8.30 = 8.00 + 0.30 (Hours + Minutes).

Ignore the decimal part in 0.30.

Convert 30 min in hrs

30/60 = 1/2 hrs

Now add 8+1/2 = 17/2

Just remember the angle traced by formulae.

Sweety said: (Sep 12, 2013)  
Why (11/2) *min-30* hrs is not working in 4:40?

Imdunb-_- said: (Sep 7, 2014)  
Look at the clock -_- it simply can't be 75 deg it has to be 60deg.
Since 6-9 is 90deg.

And can be divided in 3 intervals.
i.e. 6-7 , 7-8, 8-9.

So obviously u divide 90 by 3 ie. 30deg each.
So when its 8:30.

Hour hand on 8.
Minute hand on 6.

So it covers 2 intervals of 30deg.
HENCE 60 degree

Divya said: (Nov 23, 2014)  
Using formula is quite easy method friends.

Gourav Kulkarni said: (Jan 20, 2015)  
Clock is divided into 60 equal minute division.

1 minute division = 360/60 = 6 degree. So for 8:30.

Minute hand is on 6 while hr hand is in middle of 8 and 9.

6-7 = 5min = 5*6 = 30 degree.

7-8 = 30min.

8-8.5 = 15 min.

Total angle = 6-7+7-8+8-8.5.

= 30+30+15.

= 75 degree.

Goutham ( I Puc ) Rv Pu College said: (Oct 12, 2015)  
Guys to solve the angle between the hour hand and the min hand :

For Ex:

Let the time be 8:30 so that the hour hand is slightly far from 8 and the min hand points exactly on 6. Then the degrees between two no. S is 30 degrees (hour hand).

Now, the angle between hour hand (approximately at 8) and at 6 (min hand) is 60 degrees. Now consider only the min hand (on 6).

Now do k*30 (30 because the min hand is at 6 and k is a constant having a value of 0.5). Therefore it becomes 30*0.5 gives 15 degrees. Add these 15 degrees to 60 degrees which we got earlier. Therefore it become 60+15 = 75 degrees.

Explanation is big but am sure I will understand.

Sopu said: (Nov 27, 2015)  
If the time is 1.5 then what is the angle between hour hand and minute hand?

Manab said: (Jan 14, 2016)  
Formula for 30(h-m/5)+m/2?

Abinash Das said: (Jan 22, 2016)  
1 hr = 60 min.

8 hr = 60*8 = 480.

30 min = 480+30 = 510 hr.

Angle traced by hour hand = 510 hr/2 = 255.

Angle traced by min hand = 360/60*30 = 180.

= 255-180 = 75.

Imantu said: (Apr 13, 2016)  
Yes, it is very simple with formula, everyone can do it.

Tayza said: (Sep 29, 2016)  
@Manab.

Can you explain me? How was the formula formed?

Asad said: (Oct 6, 2016)  
No formula required, just 9 o clock is 45 degree, center of 9 and 7 is 8 simple 75 degree.

Rahul said: (Nov 9, 2016)  
How is it possible as 1min = 6 degree?
=> 10 mins= 60 degree.

So, solution is wrong.

Naveen said: (Jan 6, 2017)  
Simple way to find out the degrees is 8:30

Step1: Multiply hour and min= 8 * 30 = 240.
Step:2: Now multiply 30*11/2 = 165.
Step3: Subtract 240 -165= 75° ->answer.

Mithun said: (Jan 27, 2017)  
How to find the angle when time is 7.40 using 30 * h- (11/2) * Min?

Vishnu said: (May 19, 2017)  
To find the angle between the times 1.05,2.10,3.15,4.20,5.25, 6.30,7.35,8.40,9.45,10.50,11.55 and 12.60 only takes the half of the minutes.

For 1.05=2.50, 2.10=5 and so on.

Raghavendra said: (Jun 12, 2017)  
θ =| 11/2 M - 30H | where M = 30 and H =8.
θ = | 11/2 * 30 - 30*8 |,
θ = | 165 - 240 |,
θ = | -75|,
θ = 75°.

Pranoti said: (Jun 24, 2017)  
30*Hours-5.5*Minutes.
=30 * 8-5.5*30,
=240-165,
=75°.

Nawaz Basha said: (Jun 27, 2017)  
Find out the angle of 2hrs 45 mins?

Rohit Singh said: (Jul 30, 2017)  
What are the Angles of 7hrs 30 mins?

Ayush Jain said: (Sep 25, 2017)  
we can do by formula also-
30 (H)-11/2(M)
= 30(8)-11/2(30),
= 240-165,
= 75.

Ace said: (Nov 4, 2017)  
It is very easy new method.

In 1 minute your hand covers 1/2° while minute hand 6°.

Multiply 30 (1/2) for degree covered by your hand =15°.

And 10 min (6°) for degree by minute hand=60°.

Just add them 60+15=75°.

Any doubts.

Asinha said: (Sep 20, 2018)  
How to calculate angle in 8:35?

Could anyone help me out?

Anomiee said: (Jan 26, 2019)  
@Asinha.

8.30 hrs = 8hrs+30mins.
= ( 8+(30/60) )mins.
= (8+1/2)mins= 17/2 minutes.

Spartan said: (Mar 7, 2019)  
Here we have to find angle b/w 8.30.

The speed of minute hand= 6.
The speed of hour hand = 0.5.

The distance b/w each no is =30 i.e, 360%12 = 30;.

Sol : Hour hand: 8*30 = 240.
And 30*0.5 = 15.
Minute Hand
30*6 = 180.
255 - 180 = 75.

Dibyaranjan Sahoo said: (Mar 12, 2019)  
30 * 8 - 11/2 * 30,
240-165.
= 75.

Ravi Sharma said: (Apr 8, 2019)  
We can use this formula for this type of questions.

Angle= 30H - (11/2)*M.
Where H is hour and M is minute.
So, 30*8- (11/2)*30 = 75 ans.

Note: If the answer is minus then ignore minus or reverse this formula.

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