FINDING PERCENT INCREASE WORKSHEET

Problem 1 : 

Due to increase in demand, the price of an item is increased from 80 cents to 1.4 dollars. Find the percentage increase in price. 

Problem 2 : 

Sally is in a long-jump competition. Her first jump and second jump are 5.6m and 6.3m respectively. Find the percentage increase in her jump length. 

Problem 3 : 

6 months ago the height of a plant was 12 inches and. The height of the plant today is 4 feet. Find the percentage change in height.

Problem 4 : 

The length and width of a rectangle are increased by 10% and 5% respectively. Find the percentage increase in area.

Problem 5 : 

In a triangle, if the height is increased by 50%, what percentage of the area will be increased ?  

Detailed Answer Key

Problem 1 : 

Due to increase in demand, the price of an item is increased from 80 cents to 1.4 dollars. Find the percentage increase in price. 

Solution :

Amount of change  =  1.4 dollars - 80 cents

=  140 cents - 80 cents

=  60 cents

Percentage change is 

=  (Amount of change / Original amount) x 100 %

=  (60 / 80) ⋅ 100%

=  75%

So, the percentage increase in price of the item is 75.

Problem 2 : 

Sally is in a long-jump competition. Her first jump and second jump are 5.6m and 6.3m respectively. Find the percentage increase in her jump length. 

Solution :

Amount of change  =  Greater value - Lesser value 

=  6.3 - 5.6

=  0.7

Percentage change is 

=  (Amount of change / Original amount) x 100 %

=  (0.7 / 5.6) ⋅ 100%

=  12.5%

So, the percentage increase in her jump length is 12.5. 

Problem 3 : 

6 months ago the height of a plant was 12 inches and. The height of the plant today is 4 feet. Find the percentage change in height. 

Solution :

Amount of change :

=  4 feet - 12 inches

=  (4 ⋅ 12) inches - 12 inches

=  48 inches - 12 inches

=  36 inches

Percentage change is

=  (Amount of change / Original amount) ⋅ 100 %

=  (36 / 12) ⋅ 100%

=  3 ⋅ 100%

=  300%

So, the height of the plant is increased by 300%. 

Problem 4 : 

The length and width of a rectangle are increased by 10% and 5% respectively. Find the percentage increase in area.  

Solution :

Let l and w be the original length and width of the rectangle. 

Then, the area is lw.

After the length and width of the rectangle are increased by 10% and 5% respectively, the area is 

=  (1.1l)(1.05w)

=  1.155lw

Amount of change  =  Greater value - Lesser value 

=  1.155lw - lw

=  0.155lw

Percentage change is 

=  (Amount of change / Original amount) ⋅ 100 %

=  (0.155lw / lw) ⋅ 100%

=  0.155 ⋅ 100%

=  15.5% 

So, the area of the rectangle will be increased by 15.5%.

Problem 5 : 

In a triangle, if the height is increased by 50%, what percentage of the area will be increased ?   

Solution :

Let b and h be the original base and height of the triangle respectively.

Then, the area of the triangle is

=  bh / 2

=  0.5bh

If the height is increased by 50%, then the area of the triangle is 

=  b(1.5h) / 2

=  1.5bh / 2

=  0.75bh

Amount of change : 

=  0.75bh - 0.5bh

=  0.25

Percentage change is

=  (Amount of change / Original amount) ⋅ 100 %

=  (0.25bh / 0.5bh) ⋅ 100%

=  (0.25 / 0.5) ⋅ 100%

=  50%

So, the area of the triangle will be increased by 50%.

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