Percentage questions formula and tips

Safalta Expert Published by: Saksham Chauhan Updated Tue, 22 Mar 2022 02:33 PM IST

Highlights

The word "percent" literally means "out of a hundred." Percentages, like fractions and decimals, are used in mathematics to describe components of a whole. When working with percentages, the entire thing is divided into one hundred equal pieces. Check here at Safalta.com

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The word 'percent' literally means 'out of a hundred.' Percentages, like fractions and decimals, are used in mathematics to describe components of a whole. When working with percentages, the entire is divided into one hundred equal pieces.

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How to Calculate Percentages:

Most percentage tests will need you to execute one of two calculations: % added or percentage subtracted.

You'll need to know the % added if you're figuring out how much gratuity you should pay. That is, you will calculate a percentage of what you paid and pay that amount in addition to the principle.

So, if you paid \$26 for a lunch and wanted to tip 15%, you would multiply 26*.15 to get 3.9 and then pay \$3.90. To incorporate the original amount, we may simplify this operation by swapping 1.15 for.15. In such scenario, multiply 26 by 1.15 to arrive at 29.90, which is your total.

However, it's possible that you're calculating % off.

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You'll need to know how to remove a percentage from the principal amount if you're paying with a coupon. Assume you have a voucher for a 15% discount on a \$18 movie theatre ticket. To obtain 2.7, multiply 18*.15 and deduct \$2.70 from the result. However, if you have a 15% discount coupon, you should be aware that you are only paying 85%, in which case you may just multiply 18*.85 to get your total

price straight immediately.

Percentage Increase/Decrease Calculation:

You may be required to compute % increases or decreases on occasion. Use caution while employing the strategies outlined above. This is a unique situation that necessitates a unique formula. You'll need to use the following formula to calculate the percentage increase or decrease:

*100 (old-new)/(old)

Let's put this to the test. Imagine Crispy Chips decided to save money by putting 15% fewer chips in each bag. What is the weight of the bag now, if they started with 50g?

(50-x)/(50)*100=15

(50-x)/(50)=.15

50-x=7.5

x=42.5g

You may use the same formula to raise by a percentage. Simply enter the numbers and solve as usual. Increase/Decrease in Percentage:

Question 1:

The percentage of metals in a mine of lead ore is 60%. Now the percentage of silver is 3/4% of metals and the rest is lead. If the mass of ore extracted from this mine is 8000kg. The mass (in kg) of lead is:

Option 1: 4763

Option 2: 4764

Option 3: 4762

Option 4: 4761

2:
4764

Explanation:

Let the mass of lead be 100 units. Then, Metals = 60 unit

Silver in the metal = 60 x (3/(4x100)) = 9/20 unit

Lead in the metal = 60 - 9/20 = (1200 - 9)/20 = 1191/20 units According to the question, 100 units represent 8000 kg. 1 unit=80kg.

1191/20 unit = 80 x (1191/20) =4x1191=4764kg.

Question 2:

(0.756 x 3/4) terms of rate percent is equivalent to?

Option 1: 50.7%

Option 2: 54.7%

Option 3: 53.7%

Option 4: 56.7%

4:
56.7%

Explanation:

(0.756 x 3/4) = (756/1000) x (3/4) x 100 % = 56.7%

Question 3:

? x 15 = 37.5% of 220

Option 1: 5.5

Option 2: 5.6

Option 3: 5.25

Option 4: 5.05

1
: 5.5

Explanation:

Let N x 15=37.5%of220

⇒ 15N =(37.5 x 220) / 100 ∴N=(37.5x220)/(100x15)=5.5

Question 4:

The number .05 is how many percent of 20 ?

Option 1: 25

Option 2: 0.25

Option 3: 0.025

Option 4: 0.0025

2:
0.25

Explanation:

Lety%of 20=.05 Then, (y x 20)/100 = .05 ∴y=.25

Question 5:

What is 25% of 25% equal to?

Option 1: 0.0625

Option 2: 0.625

Option 3: 0.00625

Option 4: 0.000625

2:
0.625

Explanation:

25% of 25% = (25/100) x (25/100) = 625/10000 = 0.625

Question 6:

? % of 250 + 25% of 68 = 67

Option 1: 10

Option 2: 15

Option 3: 20

Option 4: 25

3: 20

Explanation:

Let Y% of 250 + 25% of 68 = 67 ⇒ (Y x 250)/100 + (25 x 68)/100 = 67 ⇒ 5Y/2 = 50 ∴ Y = (50 x 2) / 5 = 20

Question  7:

30% of 140 = ? % of 840 ?

Option 1: 5

Option 2: 10

Option 3: 15

Option 4: 20

1
: 5

Explanation:

Let y % o f840 = 30 % of 140

⇒ (y/100) x 840 = (30/100) x 140

∴y=(30x140x100)/(100x840)=5

Question 8:

The fraction equivalent to 2/5% is ?

Option 1: 1/25

Option 2: 1/5

Option 3: 1/125

Option 4: 1/250

4
: 1/250

Explanation:

2/5% = (2/5) /100 = 1/250

Question  9:

?%of130=10.4?

Option 1: 8

Option 2: 80

Option 3: 0.8

Option 4: 0.08

1:
8

Explanation:

Let Y % of 130=10.4 ⇒(Yx130)/100=10.4 ∴Y=(10.4x100)/130=8

Question 10:

What percent of 7.2 kg is 18 gms ?

Option 1: 2.5%

Option 2: 25%

Option 3: 0.25%

Option 4: 0.025%

3
: 0.25%

Explanation:

.2 kg = 7.2 x 1000000 gm = 7200000 gms

Required percentage = (18/7200000) x 100 % = 0.25%

Question 12:

.025 in terms of rate of rate per cent is ?

Option 1: 0.25%

Option 2: 2.5%

Option 3: 0.025%

Option 4: 25%

2:
2.5%

Explanation:

.025 = (25/1000) x 100% = 2.5%

Question 13:

At an election there were two candidates. A candidate got 38% of the vote and lost by 7200 votes. The total number of valid votes were

Option 1: 16200

Option 2: 30000

Option 3: 13000

Option 4: 13800

Explanation:

Question 14:

If 8% of x = 4% of y,then 20% of x is

Option 1: 40% of y

Option 2: 80% of y

Option 3: 10% of y

Option 4: 16% of y

3: 10% of y

Explanation:

Question 15:

The ratio between the ages of Ram and Rahim is 10:11. What% of Ram's age is Rahim's age?

Option 1: 109 1/11 %

Option 2: 110%

Option 3:  111 1/9%

Option 4: 111%

2:
110%

Explanation:

Required Percentage = 11×100/10=110% So, The correct option is 2.

Question 16:

If the radius of a sphere be doubled, then the percentage of increase in volume is

Option 1: 600%

Option 2: 800%

Option 3: 500%

Option 4: 700%

Explanation:

Question 17:

51% of the whole number is 714. 25% of that number is

Option 1: 450

Option 2: 550

Option 3: 250

Option 4: 350

4:
350

Explanation:

Question 18:

A man gives 50% of his money to his son and 30% to his daughter. 80% of the rest is donated to a trust. If he is left with ` 16,000 now, how much money did he have in the beginning?

Option 1: 8,00,000

Option 2: 4,00,000

Option 3: 40,000

Option 4: 80,000

Explanation:

Question 19:

The population of a town increases by 5% every year. If the present population is 9261, the population 3 years ago was

Option 1: 5700

Option 2: 6000

Option 3: 7500

Option 4: 8000

4
: 8000

Explanation:

Population 3 yrs. Ago

Question 20:

The price of cooking oil increased by 25%. Find by how much percentage a family must reduce its consumption in order to maintain the same budget?

Option 1: 70%

Option 2: 20%

Option 3: 30%

Option 4: 80%

2:
20%

Explanation:

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