Logical Sequence of Time


Logical Sequence of Time - Concepts
Class - 8th IMO Subjects
 
 
Concept Explanation
 

Logical Sequence of Time

Logical Sequence Of Time: Sequence simply implies arrangement of occurrence of events in accordance to the passage of time. That is to say, that which event occurs at what time followed and preceded by which events and at what times and so on so forth. To solve such problems, a base time is convenient in accordance to the conditions specified in the questions. The times of occurrence of all other events are measured in reference to the base time. The key to solving these questions is to use common sense and overall logical reasoning. All this, of course, is better explained by the use of examples which are given below.

Illustration:  A bus for Delhi leaves after every thirty minutes. An enquiry clerk told a passenger that the bus had already left ten minutes ago and the next bus would leave at 9:35 a.m. At what time did the enquiry clerk give this information to the passenger?

A. 9:10 a.m.              B. 8:55 a.m.              C. 9:05 a.m.          D. 9:15 a.m.

Answer: D

Sol.  The next bus will leave at 9:35 a.m. As this is the only concrete time given in the question, let this be the base time. This means that the previous bus had left at 9:05 a.m. But it happened ten minutes before the clerk gave the information to the passenger. Thus, the enquiry clerk gave the information at 9: 15 a.m.

Hence, the correct choice is (4).

Illustration:  At 8 p.m. on Thursday. Kiran's watch was slow by 5 minutes. But at 8 a.m. on Sunday. it was fast by 10 minutes. At what time did it give the right time?

A. 8 p.m. on Saturday              B. 4 p.m. on Friday               C. 12 noon on Saturday             D. 12 a.m. on Friday

Answer: B

Solution: From 8 p.m. on Thursday to 8 a.m. on Sunday, there are 2 complete days and one half day, i.e. 2 X 24 + 12 = 60 hours gap, and the watch gains (5 + 10) 15 minutes. In the time the non defective clock registers a time span of 60 hours,

So 15 minutes are gained in 60 hours

or   1 minute is gained in 60/15 = 4 hours

or   5 minutes are gained in = 4 X 5 = 20 hours

Let the base time be 8pm on Thursday and adding 20 hours we will get 4pm on Friday

Thus, the correct time will be on 4:00 p.m. on Friday. Hence, answer option B is correct.

Ex, 3 Satisfy remembers that his brother's birthday is after fifteenth but before eighteenth of Feburary whereas his sister Kajal remembers that her brother's brithday is after sixteenth but below nineteenth of Feburary. On which day in feburary is Satish's brother's brithday?

(a) 16th                 (b) 17th                   (c) 18th                       (d) 19th               (e) None of these

Sol. Accordinf to Satish, the brother's birthday is on one of the days among 16th and 17th February.

According to kajal, the brother's birthday is on one of the days among 17th and 18th February.

Clearly, Satish's brother's birthday is on the day common to both the above groups, i.e. 17th February.

hence, the answer is (b)

Ex. 4 If the seventh day of a month is three days earlier than Friday,  will it be on the nineteenth day of the month?

(a) Sunday                 (b) Monday                 (c) Wednesday                    (d) Friday

Sol. As, mentioned, the seventh day of the month is three days earluier than Friday, which is tuesday.

So, the fourteenth day is also Tuesday and thus, the nineteenth day is Sunday.

Hence, the answer is (a).

Sample Questions
(More Questions for each concept available in Login)
Question : 1

Ashish leaves his house at 20 minutes to seven in the morning, reaches Kunal' s house in 25 minutes, They finish their breakfast in another 15 minutes and leave for their office which takes another 35 minutes. At what time do they leaves Kunal's house to reach their office?

Right Option : B
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Explanation
Question : 2

A bus for Delhi leaves after every thirty minutes. An enquiry clerk told a passenger that the bus had already left five minutes ago and the next bus would leave at 9:35 a.m. At what time did the enquiry clerk give this information to the passenger?

Right Option : A
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Explanation
Question : 3

A bus for Delhi leaves after every thirty minutes. An enquiry clerk told a passenger that the bus had already left ten minutes ago and the next bus would leave at 11:00 a.m. At what time did the enquiry clerk give this information to the passenger?

Right Option : D
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Explanation
 
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