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SSC Past Questions Solved   - Problems on Clocks   1. The bus for Chennai leaves every 30 minutes from a bus dep...

# S.S.C. Previous Questions - Problems on Clocks

SSC Past Questions Solved   - Problems on Clocks
1. The bus for Chennai leaves every 30 minutes from a bus depot. The inquiry clerk told a passenger that the bus for Chennai left 10 minutes ago and the next bus will leave at 10: 30 am, what was the time when the inquiry clerk told this?                                                                                                                                                           [SSC (10 + 2) 2012]
a) 10: 10 am           b)10 : 20 am           c)9 :50  am                       d)10 : 00 am
Explanation :
Next bus is at 10:30 a.m.  And the bus for Chennai leaves every 30 minutes.
So last bus has left 30 minutes before 10: 30 a.m. => 10:00 a.m
When the passenger enquired, the clerk answer the bus left 10 minutes ago.
\ Enquiry time = 10:00 a.m + 10 min
= 10: 10 a.m

2.    In Ravi’s clock shop, two clocks were brought for repairs. One clock has the cuckoo coming out every 16 min, while the other one has the cuckoo coming out every 18 min. Both cuckoos come out at 12: 00 noon. When will they both come out together again?                                                                                                                             [SSC CGL 2011]
a)    2: 32 PM              b)2: 24 PM     c)2: 04 PM     d)2: 06 PM
Explanation :
The cuckoos of both the clocks will come out together after intervals which are common multiples of 16 min and 18 min.
16 = 24     18 = 2 x 32
LCM of 16 and 18 =   24 x 32 = 144 minutes
144 minutes = 2 hours + 24 minutes
Both the cuckoos come out together at 12:00 p.m
Again they will immediately come out at => 12: 00 PM + 2 hours 24 minutes
= 2: 24 PM

3.    At what time are the hands of the clock together between 6 and 7?                  [SSC CGL 2011]
a)32 $\frac{8}{11}$ minutes  past 6             b)34 $\frac{8}{11}$ minutes past 6
c)30$\frac{8}{11}$ minutes past 6              d)32 $\frac{8}{11}$ minutes past 6
Explanation :
At 6 O’ clock, the two hands are 30-minute spaces apart.
To be together, the minute hand has to gain 30-minute spaces over the hour hand.
The minute hand gains 55-minute spaces in 60 minutes.
To gain 1-minute space, the minute hand takes $\frac{60}{55}$ minutes.
To gain 30 minute spaces, it takes   30 x $\frac{60}{55}$ = 30 x $\frac{12}{11}$
= 32 $\frac{8}{11}$ minutes
At   6: 32 $\frac{8}{11}$, the two hands of a clock are together between 6 and 7

4.    A clock gains five minutes every hour. What will be the angle traversed by the second hand in 1 min?                                                                                                 [SSC CGL 2011]
a)360                                  b)360.50                    c)390                    d)380
Explanation :
In one second, the second-hand makes an angle of 60.
The clock gains 5 minutes every hour. Then the minute hand of the clock moves 65 minutes in one hour.
So seconds hand also moves 65 seconds.
Therefore, the angle covered by the second hand = 65 x 60 = 3900

5.    The chairman of the Selection Committee arrived at the interview- room for conducting an interview at 10 minutes to 12: 30 h. He was earlier by 20 minutes than the other members of the board, who arrived late by 30 min. At what time was the interview scheduled?     [SSC  Previous Question 2005]
a)12: 10                       b)12: 20                            c)12 : 30                            d) 12: 40
Explanation :
The chairman of the selection committee arrived at 10 minutes to 12 :30 => 12 : 20
He was earlier by 20 minutes than the other members.
So other members arrived at => (12 : 20 + 20 minutes)= 12 : 40
Other members were late by 30 minutes
So scheduled time of interview = (12 : 40 – 30 minutes) = 12 :10

6.    By looking in a mirror, it appears that it is 6: 30 in the clock. What is real-time?
[SSC Past Qustion 2005]
a)6 : 30                             b)5 : 30                  c)6 : 40                           d)5 : 00
Explanation :
The mirror reflection shows the time 6 :30
The actual time = (12 hours - 6 : 30 ) or (11 : 60 – 30 minutes)
= 5 : 30

7.    Reaching the place of meeting 20 minutes before 8: 50 hours, Satish found himself 30 minutes earlier than the man who came 40 minutes late. What was the scheduled time of the meetings?                                                                             [SSC (10 + 2) 2002]
a) 08: 20                    b)08 : 10                            c) 08: 05                          d) 8: 00
Explanation :
Satish reached the place of meeting 20 minutes before 8: 50
So he reached at    =>  (8: 50 – 20 minutes) = 08: 30
Satish was 30 minutes earlier than the man who came 40 minutes late.
So Satish was 10 minutes late.
\ Scheduled time of the meeting = (8: 30 - 10 minutes)
= 8: 20

8.  A clock goes fast by 1 minute during the 1st hour, by 2 minutes at the end of the 2nd hour, by 4 minutes at the end of 3rd hour, by 8 minutes by the end of 4th hour, and so on. At the end of which hour, will it be fast by just over 60 min?                     [SSC (10 + 2) 2002]
a)Fifth                      b)Sixth                              c)Seventh                        d) Eighth
Explanation :
A clock goes fast by 1 minute during the 1st hour, by 2 minutes at the end of the 2nd hour, by 4 minutes at the end of 3rd hour, by 8 minutes  by the end of 4th hour and so on.
Every hour, the clock gains the double the time it gained in the previous hour.
At the end of the first hour => 1 minute
At the end of second hour => 2 minutes
At the end of the third hour =>  4 minutes
At the end of fourth hour => 8 minutes
At the end of the fifth hour => 16 minutes
At the end of the sixth hour => 32 minutes
At the end of seventh hour => 64 minutes
Therefore, at the end of 7th hour, the clock will be fast by just over 60 min.

9.  A clock goes slow from mid-night by minutes. At the end of the 1st hour, by 10 min at the end of the 2nd hour by 10 min, by 15 min at the end of the 3rd hour and so on. What will be the time by this clock after 6 h?                                                                            [SSC (10 + 2) 2002]
a)6 : 00 a.m                     b)5 : 30 a.m                       c)6 : 30 a.m                d) 5 : 15 a.m
Explanation:
The clock loses 5 minutes in 1st hour, l10 minutes at the end of the second the hour and loses 15 minutes at the end of the third hour and so on.
The  clock loses 5 minutes every hour.
In 6 hours, the clock loses  by ( 6 x 5 ) = 30 minutes
The clock was correct at midnight, and after 6 hours, the clock loses 30 minutes
So after 6 hours , the correct time is 6 a.m
The clock shows the time after 6 hours => 6 a.m – 30 minutes = 5 : 30 a.m

10.   Reaching the place of meeting on Tuesday 15 min before 08: 30 h. I found myself half an hour earlier than the man who was 40 min late. What was the scheduled time of the meeting?                                                                              [SSC (10 + 2) 2000]
a) 08: 00 h                b)08 : 05 h                        c) 08: 15 h                       d) 08: 45 h
Explanation :
I reached 15 minutes before 8:30 = 8:30 – 15 minutes = 8 : 15
I was 30 minutes earlier than the man who was 40 minutes late
I was late by=> 40 min – 30 min = 10 minutes
Therefore, scheduled time = 08: 15 – 10 minutes
= 08: 05 h
11.   Kamala would like to complete all her homework before 10.00 pm to watch and important TV program. She has 40 min assignment in each of her five prepared subjects. What is the latest time at which she can start and still complete her homework in the time of the program?                                                 [SSC (10 + 2) 2000]
a) 6: 40 pm                   b) 6: 30 pm                  c) 7: 10 pm              d) 7: 20 pm
Explanation :
TV Programme is at 10:00 p.m
She has to complete 5 assignments each of 40 minutes.
Time is taken to complete the assignments = 5 x 40 minutes
= 3 h 20 min
So the latest time at which she can start is = (10: 00 - 03: 20) = 06: 40 pm

12.   After 9 O’clock at what time between 9 pm and 10 pm will the hour and minute hands of a clock point in opposite directions?
[SSC CGL 2000]
a)15 min past 9      b)16 min past 9    c)16 $\frac{4}{11}$  min past 9   d)  17 $\frac{1}{11}$  min past 9
To gain 1-minute space, the minute hand takes $\frac{60}{55}$ minutes
To gain 15 minutes spaces, it will take => 15 x $\frac{60}{55}$ = 16 $\frac{4}{11}$
Therefore, the two hands of a clock point in opposite directions after 9 O’clock at 16 $\frac{4}{11}$ min past 9.