WORD PROBLEMS ON PERCENTAGE

Problem 1 :

John paid $64 for an item after 20% discount. Find the price of the item without discount.

Solution :

Let x be the price of the item without discount.

Given : John paid $64 for the item after 20% discount.

Then, we have

(100 - 20)% of x = 64

0.8x = 64

Divide each side by 0.8.

x = 80

So, the price of the item without discount is $80.

Problem 2 :

If A's salary is  20% less than B's salary. By what percent is B's salary more than A's salary?

Solution :

Let us assume B's salary = $100 ----(1)

Then, A's salary = $80 ----(2)

Now we have to find the percentage increase from (2) to (1).

Difference between (1) and (2) = $20.

Percentage increase from (2) to (1) is

= (20/80) ⋅ 100%

= 25%

Hence,  B's salary is 25% more than A's salary.

Problem 3 :

In an election, a candidate who gets 84% of votes is elected by majority with 588 votes. What is the total number of votes polled?

Solution :

Let "x" be the total number of votes polled.

Given : A candidate who gets 84% of votes is elected by majority of 476 votes

From the above information, we have

84% of x = 588 ----> 0.84x = 588

x = 588/0.84

x = 700

Hence,  the total number of votes polled 700.

Problem 4 :

When the price of a product was decreased by 10 % , the number sold increased by 30 %. What was the effect on the total revenue?

Solution :

Before decrease in price and increase in sale,

Let us assume that price per unit = $100.

Let us assume that the number of units sold = 100.

Then the total revenue = 100 ⋅ 100 = 10000 ----(1)

After decrease 10 % in price and increase 30 % in sale,

price per unit = $90

number of units sold = 130

Then the total revenue = 90 ⋅ 130 = 11700 ----(2)

From (1) and (2), it is clear that the revenue is increased. 

Difference between (1) and (2) = 1700.

Percent increase in revenue is

 = (Actual increase/Original revenue) ⋅ 100%

= (1700/10000) ⋅ 100%

= 17 %

Hence,  the net effect in the total revenue is 17% increase. 

Problem 5 :

A student multiplied a number by 3/5 instead of 5/3. What is the percentage error in the calculation?

Solution :

In the given two fractions, the denominators are 5 and 3.

Let us assume a number which is divisible by both 5 and 3.

Least common multiple of (5, 3) = 15.

So, let the number be 15.

15 ⋅ 3/5 = 9 ----(1) ----> incorrect

15 ⋅ 5/3 = 25 ----(2) ----> correct

Difference between (1) and (2) is 16.

Percentage error is

= (Actual error/Correct answer) ⋅ 100%

= (16 / 25) ⋅ 100%

= 64%

Hence,  the percentage error in the calculation is 64%.

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