Clocks and Calendars
- At what time between 9 o'clock and 10 o'clock, will the hands of a clock be in the same straight line but not together ?
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At 9 o'clock, the hour hand is at 9 and the minute hand is at 12. it means that the two hands are 15 min spaces apart .To be in the same straight line (but not together ), they will be 30 min space apart .
∴ The minute hand will have to gain (30 - 15) = 15 min space over the hour hand .Correct Option: C
At 9 o'clock, the hour hand is at 9 and the minute hand is at 12. it means that the two hands are 15 min spaces apart .To be in the same straight line (but not together ), they will be 30 min space apart .
∴ The minute hand will have to gain (30 - 15) = 15 min space over the hour hand .
As we Know, 55 min spaces are gained in 60 min.
∴ 15 min will be gained in (60/55 x 15) min = 180/11 = 164 /11 min
Hence, the hands will be in the same straight line but not together at 164/ 11 min past 9.
- At what time between 2 o'clock and 3 o'clock, will the hands of a clock point in opposite directions ?
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Given that n = 2 and (n + 1) = 3(n < 6)
The hands will be at the same straight line at
⇒ (5n + 30) x 12/11 min past n.Correct Option: A
Given that n = 2 and (n + 1) = 3(n < 6)
The hands will be at the same straight line at
⇒ (5n + 30) x 12/11 min past n.
⇒ (5 x 2 + 30 ) x 12/11 min past 2.
⇒ (10 + 30) x 12/11 min past 2.
⇒ 40 x 12/11 min past 2.
⇒ 480/11 min past 2.
- A clock is set right at 6 am. The clock losses 16 min in 24 h. What will be true time. if the clock indicates 11 pm on 4th day?
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Time from 6 am on a day to 11 pm on 4th day = 89 h
Now, 23 h 44 min of this clock = 24 h of correct clock
89 h of this clock = 24 x (15/356) x 89 h of correct clock = 90 h of correct clockCorrect Option: A
Time from 6 am on a day to 11 pm on 4th day = 89 h
Now, 23 h 44 min of this clock = 24 h of correct clock
89 h of this clock = 24 x (15/356) x 89 h of correct clock = 90 h of correct clock
∴ Correct time will be 12 o' clock (mid-night).
- A clock is set right at 9 pm. The clock gains 10 min in 24 h. What will be true time, when the clock indicates 2 pm on the following day?
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Time from 9 pm in a day to 2 pm on the following day = 29 h.
24 h 10 min of this clock = 24 h of the correct clock
or 145/6 h of this clock = 24 h of the correct clock
29 h of this clock = 24 x (6/145) x 29 h of the correct clock
= 28 h 48 min of correct clockCorrect Option: C
Time from 9 pm in a day to 2 pm on the following day = 29 h.
24 h 10 min of this clock = 24 h of the correct clock
or 145/6 h of this clock = 24 h of the correct clock
29 h of this clock = 24 x (6/145) x 29 h of the correct clock
= 28 h 48 min of correct clock
∴ The correct time is 28 h 48 min after 9 am. This will be 48 min past 1.
- The minute hand of a clock overtakes the hour hand at intervals of 70 min of the correct time. How much in a day does the clock gain or loss?
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Given that, time to overtake = 70 min
The required result = [(720/11) - N) ] x [(60 x 24)/N) min
= [(720/11) - 70) ] x [(60 x 24)/70) minCorrect Option: B
Given that, time to overtake N = 70 min
The required result = [(720/11) - N) ] x [(60 x 24)/N) min
= [(720/11) - 70) ] x [(60 x 24)/70) min
= [(720 - 770) / 11] x [(60 x 24) / 70] min
= - (50/11) x [(6 x 24)] / 7 min = -7200/77 min
-ve sign indicates that there is a loss.