USING PERCENT OF CHANGE WORKSHEET

About "Using percent of change worksheet"

Using percent of change worksheet :

Worksheet on using percent of change is much useful to the students who would like to practice solving word problems on percents.

Using percent of change worksheet - Problems

1. The grizzly bear population in Yellowstone National Park in 1970 was about 270. Over the next 35 years, it increased by about 115%. What was the population in 2005 ?

2.  Mr. David is running a business firm and he made \$12000 profit last year. If the profit for this year is 20% less than the last year, find the profit for this year.

3.  If an amount of \$100 in a savings account increases by 10%, then increases by 10% again, is that the same as increasing by 20% ?

4.  A trader marks his goods 20% above the cost price and allows a discount of 10% for cash. Find the profit percentage.

5.  A person wants to get 20% profit after selling his object at 20% discount. Find the required percentage increase in marked price.

Using percent of change worksheet - Solution

Problem 1 :

The grizzly bear population in Yellowstone National Park in 1970 was about 270. Over the next 35 years, it increased by about 115%. What was the population in 2005 ?

Solution :

Step 1 :

Find the amount of change.

Find 115% of 270. Write 115% as a decimal.

1.15 × 270  =  310.5

Round to the nearest whole number.

≈ 311

Step 2 :

Find the new amount.

New Amount = Original Amount + Amount of Change

=  270 + 311

=  581

Hence, the population in 2005 was about 581 grizzly bears.

Problem 2 :

Mr. David is running a business firm and he made \$12000 profit last year. If the profit for this year is 20% less than the last year, find the profit for this year.

Solution :

Step 1 :

Find the change in profit.

Find 20% of 12000. Write 20% as a decimal.

0.20 × 12000  =  2400

Step 2 :

Find the profit for this year .

Since the profit is decreased, we have to subtract the change in profit (\$2400) from the profit of the last year (\$12000).

Profit for this year  is

=  Profit for the last year - Change in profit

Substitute values and subtract them.

=  12000 - 2400

=  9600

Hence, the profit for this year is \$9600.

Problem 3 :

If an amount of \$100 in a savings account increases by 10%, then increases by 10% again, is that the same as increasing by 20% ?

Solution :

Case (i) : Given amount is increased by 10% and again by 10%

Find the amount of change for the first 10%.

Find 10% of 100. Write 10% as a decimal.

0.10 × 100  =  10

New amount after the first increment of 10% is

=  Original Amount + Amount of Change

=  100 + 10

=  110

Increased again by 10%.

Find 10% of 110. Write 10% as a decimal

0.10 x 110  =  11

New amount after the second increment of 10% is

=  110 + 11

=  121 -----> (1)

Case (ii) : Given amount is increased by 20%.

Find the amount of change.

Find 20% of 100. Write 20% as a decimal.

0.20 × 100  =  20

New amount after the increment of 20% is

=  Original Amount + Amount of Change

=  100 + 20

=  120 -----> (2)

Conclusion :

From (1) and (2), it is clear that increasing an amount by 10%, then increases by 10% again is not the same as increasing by 20%.

Problem 4 :

A trader marks his goods 20% above the cost price and allows a discount of 10% for cash. Find the profit percentage

Solution :

Let the cost price be \$100.

Then, marked price (M.P) = \$120

Let the selling price be "X"

From the above picture, we get

90% of (M.P) = X

(0.9).120 = X

108  =  X --------> S.P  =  108

Cost price = \$100,

Selling Price = \$108 ---------> Profit % = 8%

Problem 5 :

A person wants to get 20% profit after selling his object at 20% discount. Find the required percentage increase in marked price.

Solution :

Let the cost price be \$100.

Then, the selling price = \$120

Let the marked price be "X"

From the above picture, we get

80% of (M.P) = S.P

(0.8)X  =  120

X  =  150 --------> M.P  =  150

Cost price = \$100,     Marked Price = \$150

Hence, the required percentage increase = 50%

After having gone through the stuff given above, we hope that the students would have understood "Using percent of change worksheet".

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