Page 243 - Services Selection Board (SSB) Interviews

Clocks 239

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1. (a) Same as previous question Option A is correct. directions at 6 o’ clock only). So, in a day, the hands
2. (c) point in the opposite directions 22 times.
3. (b) At 2PM angle between minute hand and hour 10. (b)
hand is 60° and that at 6PM is 180° hence percentage 11. (c) In 12 hours both hands are in straight line (either
change is 200%. coincides or in opposite direction) 22 times. Hence
4. (d) From the formula the required angle is 187.5° in 24 hours both hands are in straight line 44 times.
5. (a) 12. (c)
6. (b) Consider exactly at 8 : 00, minute hand is at 13. (a) From Sunday noon to the following Sunday at
position ‘12’ and hour hand is at ‘8’ hence angle 2 p.m there are 7 days 2 hours or 170 hours. The
between these two hands at 8 : 00 is 240°. watch gains 2 + 4 / min in 170 hrs. Therefore, the
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5
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Case (i) when minute hand is behind Hour hand watch gains 2 min in 2 ×170 hrs i.e., 50 hours 6 /
5.
then required time is (240 – 90)/(11/2) = 150/(11/2) Now 50 hours = 2 days 2 hrs. Therefore, 2 days 2
= 300/11 = 27 3/11 minute hours from Sunday noon = 2 p.m on Tuesday.
Case (ii) when minute hand is ahead of hour hand 14. (c) Time from 10 a.m on a day to 3 a.m on 4th day
then required time is (240 + 90)/(11/2) = 330/(11/2) = 24 × 3 + 17 = 89 hours.
= 330 × 2/11 = 60 minute i.e at 9 : 00 PM. Now 23 hrs 44 min. of this clock = 24 hours of
7. (b) 28 × 2 × 6 = 336 degree correct clock.
8. (b) The minutes hand to coincide with the hour hand Or 356 / 15 hrs of faulty clock = 24 hours of correct
it should trace at first 5 minute spaces and then the clock.
hands of the clocks to be opposite to each other
minute hand should trace 30 minute spaces i.e. 89 hrs of faulty clock = (24 × 15/356 × 89) hrs =
totally it should gain 5 + 30 = 35 minute spaces to 90 hrs.
be opposite to that of hour hand. So, the correct time is 11 p.m
We know that, Minute hand gains 55 minute spaces 15. (b) Time from 12 p.m. on Sunday to 2 p.m. on the
over hour hand in 1 hour. Therefore, Minute hand following Sunday = 7 days 2 hours.
gain 40 minute spaces over hour hand in 35 × = 24 × 7 + 2 = 170 hours.
(60/55) = 38(2/11). The watch gains = (2 + 4 × 4/5)min = 34 / 5 minute
Hence the hand of the clock will minutes be opposite in 170 hrs.
to each at 38 (2/11) past 1’O clock. Therefore, Since, 34/5 min are gained in 170 hrs.
Correct option is B.
2 min are gained in(170 × 5/34 × 2) hrs = 50 hours
9. (b) The hands of a clock point in opposite directions i.e 2 days 2 hrs. after 12 p.m. on Sunday i.e., it will
(in the same straight line) 11 times in every 12 hours. be correct at 2 p.m. on Tuesday.
(Because between 5 and 7 they point in opposite