ஞாயிறு, 15 நவம்பர், 2015

TNPSC :shortcut techniques for percentage

Now we decide to start a new campaign that will help's our reader who are preparing forGovernment jobs as well as for Bank jobs. Our team will try to write some very helpful articles related to various shortcut techniques related to the aptitude. Here in this post we will share various shortcut techniques for percentage

 



Shortcut 1: If we increased any value by x % and then decreased by y %. Then the resulting effect in percent will be:  "+ x + y + xy /100".

 

Various Examples related to this Percentage Short cuts are given below:

Example 1:  The price of goods is marks 20% more than the real price by the shopkeeper. After that the shopkeeper allowed a discount of 10%. Now What profit or loss did the shopkeeper will get?

Solution: We solve this as follow by using the percentage shortcut1 as follow:

The Loss (or) Profit he will get is = 20 – 10 + (+20)(-10)/100

                                                     = + 8% (profit).

 

Example 2: Side of the square is increased by 30%. Find the percentage increase in area.

Solution: Here we again use the percentage shortcut 1.

So the increased area percentage = 30 + 30 + (30)(30)/100

                                                   = 69 % (increased).

 

Example 3: Radius of the circle is decreased by 20%. What will be the percent change in area of the circle?

Solution: Therefore by using the percentage shortcut1:

The Percent change in area of circle is= - 20 - 20 + (-20)(-20)/100

                                                         = -36% (decreased)

 

Example 4: The price of a car is increased by 15% than after that again decreased by 15%. What will be the percent change?

Solution: The percent change is = + 15 - 15 + (+15)(-15)/100

                                                  = - 2.25 % (decreased)

 

Example 5: Length of a rectangle is increased by 40% and breadth of the rectangle is decreased by 40%. Find change in area.

Solution: By using the formula of percentage shortcut given above:

The percent change in area of rectangle is= 40 - 40 + (-40)(+40)/100

                                                              = -16 %( decreased)