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Alarm clock-beep LCM HCF concept


summer1350

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Can anyone please help me with the following question:

An electronic device makes beep every 60 sec. Another device makes a beep after every 62 sec. They beep together at 10 AM. The time when they will next make a beep together at the earliest is:

A) 10.30 AM

B) 10.31 AM

C) 10.59 AM

D) 11 AM

E) 11.05 AM

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  • 2 weeks later...

The question comes under ratios and proportions. Solvin them is very simple by the following method:

 

Make a table according to the question and then form an equation by that table. The table should be as below:

 

MEN DAYS TABLES

5 12 40

24 x 320

 

To form an equation, first hide the tables part and consider men and days only. You see that the no. of men are increasing, therefore, no. of days should decrease if the no. of tables are the same or constant. This forms an inversely proportion relationship between the men and days. This means that 5 will multiply by 12 and x will multiply by 24. Your equation will be

 

(5)(12)( ) = (x)(24)( )

 

(Note that the empty spaces are for the next relation between days and tables. Secondly, if the relation would have been directly proportional, then 5 would multiply by x and viceversa)

 

Now forget the mens portion or keep it constant, if the no. of tables increase, the no. of days would also increase i.e. a direct relationship thus,

 

(5)(12)(320)=(x)(24)(40)

 

or x=20 days

 

HOPE THAT HELPS

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