Aptitude - Clock - Discussion
Discussion Forum : Clock - General Questions (Q.No. 6)
6.
At what time between 7 and 8 o'clock will the hands of a clock be in the same straight line but, not together?
Answer: Option
Explanation:
When the hands of the clock are in the same straight line but not together, they are 30 minute spaces apart.
At 7 o'clock, they are 25 min. spaces apart.
Minute hand will have to gain only 5 min. spaces.
55 min. spaces are gained in 60 min.
| 5 min. spaces are gained in |  |
60 | x 5 |  min |
= 5 | 5 | min. |
| 55 | 11 |
| Required time = 5 |
5 | min. past 7. |
| 11 |
Discussion:
70 comments Page 4 of 7.
Hir@nm@y said:
8 years ago
At first you multiple 1st hours by 5 (7*5=35),
Then you substitute 30 from the multiple values, (35-30=5),
That's the answer.
5* 5/11 [by rules of (x* x/11)].
That's answer will 7: 5* 5/11
Then you substitute 30 from the multiple values, (35-30=5),
That's the answer.
5* 5/11 [by rules of (x* x/11)].
That's answer will 7: 5* 5/11
John said:
8 years ago
@Vivek Jain.
In 1 hr minute, min hand covers 60 min and hr hand covers 5 min. Comparing both minute hand gains 55 min in 1 hr.
In 1 hr minute, min hand covers 60 min and hr hand covers 5 min. Comparing both minute hand gains 55 min in 1 hr.
Bhushan suriya said:
7 years ago
(210-6a)+(30/60)a = 180.
I think this will be the perfect solution.
I think this will be the perfect solution.
Riya shah said:
10 years ago
Shortcut formula:
ANGLE = 30*H - 11/2M.
Together Means angle consider as zero.
Put into the formula.
0 = 30 * 7 - 11/2M.
11/2M = 210.
Imp together consider as zero.
ANGLE = 30*H - 11/2M.
Together Means angle consider as zero.
Put into the formula.
0 = 30 * 7 - 11/2M.
11/2M = 210.
Imp together consider as zero.
Ajeesh R Nair said:
6 years ago
@Himanshu
How min hand increases angle? Please explain.
How min hand increases angle? Please explain.
Faiz said:
1 decade ago
@Harshad
Man at 7 o clock, the hour hand is at 7 and the minute hand is in 12 i.e 60th min. assume the display in your watch is like 5 10 15.. 60.. so at 7 the hour hand will be at 35 and the min hand will be in 60.. now jus go on adding the minute space clockwise or els simple (60-35) gives 25 mins space..!!
Man at 7 o clock, the hour hand is at 7 and the minute hand is in 12 i.e 60th min. assume the display in your watch is like 5 10 15.. 60.. so at 7 the hour hand will be at 35 and the min hand will be in 60.. now jus go on adding the minute space clockwise or els simple (60-35) gives 25 mins space..!!
Himanshu dewaangan said:
1 decade ago
ANOTHER METHOD:
In 7 o'clock there are angle between hands= 5*30=150 degree
we have to make that angle = 180 degree
let after X min
min hand will increase angle by = X*6 =6X,on 150 degree
1 degree of min = 1/12 degree of hr
6X degree of min = 6X/12 = X/2 degree of hr (decrease angle on 150)
so angle have to be between hands=180
150+6X-X/2=180
x=5+5/11
ANS=(5+5/11) minute and 7 past
In 7 o'clock there are angle between hands= 5*30=150 degree
we have to make that angle = 180 degree
let after X min
min hand will increase angle by = X*6 =6X,on 150 degree
1 degree of min = 1/12 degree of hr
6X degree of min = 6X/12 = X/2 degree of hr (decrease angle on 150)
so angle have to be between hands=180
150+6X-X/2=180
x=5+5/11
ANS=(5+5/11) minute and 7 past
SHEKHAR said:
1 decade ago
@amit:11/2min-30h this formula applicable only when h<6
if u put h=6 or above then the min>60 which is not acceptable(for the 180 degree),
in this problem if we put that formula then the ans is 77(10/11)
but in that case the h=7 so we apply the another formula which is 30h-11/2
in this case if we put that then formula the ans is 5(5/11)
if u apply that formula then u will find that min<60 which is acceptable
BASICALLY WE NEED THIS 2 FORMULAS BUT IN DIFF CASE...
hope u will understand:)
if u put h=6 or above then the min>60 which is not acceptable(for the 180 degree),
in this problem if we put that formula then the ans is 77(10/11)
but in that case the h=7 so we apply the another formula which is 30h-11/2
in this case if we put that then formula the ans is 5(5/11)
if u apply that formula then u will find that min<60 which is acceptable
BASICALLY WE NEED THIS 2 FORMULAS BUT IN DIFF CASE...
hope u will understand:)
Amit said:
1 decade ago
What is the formula? whether its 11/2*min-30hr or 30hr-11/2*min?
Rajendra Sahu said:
1 decade ago
For straight line angle =180
The formula is for finding angle =30H-(11/2)*M
where H =>Hours
M => Minute.
Now
30H-(11/2)*M=180
30*7-(11/2)*M=180
210 - (11/2)*M=180
-(11/2)*M=180-210
-(11/2)*M=-30
11*M=60 (Cross Multiply)
M=60/11 minutes
means 5+5/11 minute
So Time will be
(5+5/11) minute and 7 past
The formula is for finding angle =30H-(11/2)*M
where H =>Hours
M => Minute.
Now
30H-(11/2)*M=180
30*7-(11/2)*M=180
210 - (11/2)*M=180
-(11/2)*M=180-210
-(11/2)*M=-30
11*M=60 (Cross Multiply)
M=60/11 minutes
means 5+5/11 minute
So Time will be
(5+5/11) minute and 7 past
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