Clock 1

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Basic Concepts & Short Tricks to solve Clock related Questions in Reasoning

The Reasoning section of every competitive exam includes questions from the topic “Clock”. This topic is considered to be quiet important and every year a good number of questions are asked from this topic. We are providing you with Basic Concepts & Short Tricks to solve Clock related Questions in Reasoning which will surely help you in the upcoming SSC Exams 2016.

Clock

A clock is an instrument used for indicating and maintaining the time. It is an electronic device that present the duration of hour, minute and second.
Different types of question  covered in this chapter are as follows.
  • Angle Between the Hands of clock
  • Position of Hands of clock
  • Faulty clocks
  • Time Gained or lost by clock
clock 1The clock represents two things. i.e., minutes and hour. The minute is a unit of time equal to 1/60th of an hour or 60 s i.r., 1 min = 60 s.
Clocks Concepts :
  • The dial of the clock is circular in shape and was divided into 60 equal minute spaces
  • 60 minute spaces traces an angle of 3600. Therefore, 1minute space traverses an angle of 60
  • In 1 hour, Minute hand traverses 60 minute space or 3600 ,Hour hand traverses 5 minute space or 300
  • The hands of the clock are perpendicular in 15 minute spaces apart
  • The hands of the clock are in straight line and opposite to each other in 30minute spaces apart.
  • The hands of the clock are in straight line when they coincide or opposite to each other.
  • The hands of the clock are perpendicular to each other for 22 times in 12 hours and for 44 times in a day.
  • The hands of the clock are opposite to each other for 11 times in 12 hoursand 22 times in a day.
  • The minute hand gain 55 minutes over hour hand per hour.
Hence x minute space to be gained by minute hand over hour hand can be calculated as x.(60/55) or x.(12/11)
Ex : At what time between 2’O clock and 3’O clock the hands of the clock Ware opposite to each other.
1. 34( 6/11 ) past 2’Oclock
2. 43( 7/11 ) past 2’Oclock
3. 56( 8/11 ) past 2’Oclock
4. 64(9/11past 2’Oclock
Solution:
At 2’O clock the minute hand will be at 12 as shown below
clock 2
The minutes hand to coincide with the hour hand it should trace at first 10 minute spaces and then the hands of the clocks to be opposite to each other minute hand should trace 30 minute spaces i.e. totally it should gain 10+30=40 minute spaces to be opposite to that of hour hand
We know that,
Minute hand gains 55 minute spaces over hour hand in 1 hour
Therefore, Minute hand gain 40 minute spaces over hour hand in 40 × (60/55) = 43(7/11)
Hence the hand of the clock will minutes be opposite to each at 43( 7/11 ) past 2’Oclock
Therefore, Correct option is 2′
When clock is too fast, too slow
  • If a clock or watch indicates 6 hr 10 min when the correct time is 6, it is said that the clock is 10 min too fast. If it indicates 6. 40 when the correct time is 7, it is said to be 20 min too slow.
    Now let us have an example based on this concept
Ex: My watch, which gains uniformly, is 2 min, & show at noon on Sunday, and is 4 min 48 seconds fast at 2 p.m on the following Sunday when was it correct ?
Solution:From Sunday noon to the following Sunday at 2 p.m there are 7 days 2 hours or 170 hours.
The watch gains 2+4 4/5 min in 170 hrs.
Therefore, the watch gains 2 min in  (2  *170 * 5/34) hrs i.e., 50 hours
Now 50 hours = 2 days 2 hrs.
Therefore, 2 days 2 hours from Sunday noon = 2 p.m on Tuesday.

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