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This mock test of Test: Clocks- 1 for UPSC helps you for every UPSC entrance exam.
This contains 10 Multiple Choice Questions for UPSC Test: Clocks- 1 (mcq) to study with solutions a complete question bank.
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QUESTION: 1

The reflex angle between the hands of a clock at 10.25 is:

Solution:

Angle traced by hour hand in 125/12 hrs =

Angle traced by minute hand in 25 min =

∴ Reflex angle = 360^{0} -

QUESTION: 2

**Q. **How many times in a day, the hands of a clock are straight?

Solution:

In 12 hours, the hands coincide or are in opposite direction 22 times.

∴ In 24 hours, the hands coincide or are in opposite direction 44 times a day.

QUESTION: 3

At what time between 5.30 and 6 will the hands of a clock be at right angles?

Solution:

At 5 o'clock, the hands are 25 min. spaces apart.

To be at right angles and that too between 5.30 and 6, the minute hand has to gain (25 + 15) = 40 min. spaces.

55 min. spaces are gained in 60 min.

40 min. spaces are gained in

∴ Required time = min. past 5.

QUESTION: 4

A clock is started at noom. By 10 mimutes past 5, the hour hand has turned through:

Solution:

Angle traced by hour hand in 12 hrs = 360º.

Angle traced by hour hand in 5 hrs 10 min. *i.e., 31/6 hrs *

= (360/12*31/6)°

= 155º

QUESTION: 5

A watch which gains 5 seconds in 3 minutes was set right at 7 a.m. In the afternoon of the same day, when the watch indicated quarter past 4 o'clock, the true time is:

Solution:

Time from 7 a.m. to 4.15 p.m. = 9 hours 15 min =37/4 hours

3 min 5 sec of this clock = 3 min. of the correct clock.

37/720 hours of this clock =1/20 hours of the correct clock

37hours of this clock =(1/20 x 720/37 x 37/4) hours of the correct clock.

= 9 hours of the correct clock.

The correct time is 9 hours after 7 a.m. *i.e.,* 4 p.m

QUESTION: 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?

Solution:

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

∴ Required time = min. past 7.

QUESTION: 7

A watch which gains uniformly is 2 minutes low at noon on Monday and is 4 min. 48 sec fast at 2 p.m. on the following Monday. When was it correct?

Solution:

Time from 12 p.m. on Monday to 2 p.m. on the following Monday = 7 days 2 hours = 170 hours.

∴ The watch gains in 170 hrs.

Now, 34/5 min. are gained in 170 hrs.

∴ 2 min. are gained in

Watch is correct 2 days 2 hrs. after 12 p.m. on Monday *i.e.,* it will be correct at 2 p.m. on Wednesday.

QUESTION: 8

At what angle the hands of a clock are inclined at 15 minutes past 5?

Solution:

(11*15-60*5)/2=67.5

QUESTION: 9

The angle between the minute hand and the hour hand of a clock when the time is 4.20, is:

Solution:

The angle between hour and minute hand in 4:20 is 10 degrees.

For a minute, the hour hand rotates by 30/60 = 1/2 degrees.

hence, for 20 minutes it rotates by an angle of 20*1/2 = 10 degrees.

QUESTION: 10

Solution:

Time from Monday noon (12 o' clock) to following Monday 2 pm = 7 day 2 hours

= 7×24+2

= 168+2

= 170 hours

Total time gained Monday noon (12 o' clock) to following Monday 2 pm = 2 min + 4 min 48 sec

The given watch gains 34/5 mins in 170 hours

Given that the said watch was 2 minutes low at Monday noon. Hence when it gained 2 minutes, the time was correct.

The given watch gains 34/5 mins in 170 hours

⇒ The given watch gains 2 mins in

= 5 * 5 * 2 hours = 50 hours

Hence the time was correct after 50 hours from Monday noon = after 2 days 2 hours from Monday noon = 2 pm on Wednesday

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