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CALCULATE YOUR WAITING IN A QUEUE

   

What is the probability of getting an odd number in a dice throw?  There are three odd numbers 1,3 and 5.  Hence the probability is 3/6=50%.

Draw a circle within a square



  Drop pins randomly in the square.  The pin should fall on its tip.  What is the chance of pin falling within the circle?

Area of the square = 2r*2r= 4r^2.
Area of the circle = pi r^2.
Hence the chance of a pin falling in the circle = area of the circle/area of the square.
                                                                         = pi*r^2/4*r^2
                                                                         = pi/4 = 3.14/4 = 0.7854
                                                                         =78.54%
Hence the pin mostly will fall within the circle.

     Let us assume that you are waiting in a queue in the doctor's clinic for treatment.  Let us further assume that the waiting time varies between 0 to 45 minutes and the treatment time varies between 0 to 30 minutes .  What is your chance of getting out of the clinic in 30 minutes?  Let us name the waiting time as X and the treatment time as Y, then plot a graph.




 We get a rectangle.  Your time X and Y may fall at any point in the rectangle.  Now what is your chance of total time not exceeding 30 minutes?
That is, X+Y must be less than 30.
Draw a line for the equation X+Y = 30 in the same graph.  Any point in the shaded region below the line satisfies your condition.Now what is the chance to meet our condition?

 The chance = Area of the shaded triangle/ area of the rectangle.
                     =0.5*b*h/l*b
                     =0.5*30*30/30*45
                     = 450/1350 = 0.33333
                     = 33.33%

 So the chance is 33% which is not much.  You should be prepared to wait for a longer time.
Here the probability and geometry is combined.  These kind of problems can be solved using geometry.  So statistics gives measurement for our expectations.

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