percentage is a ratio of a number or fraction to 100
percentage =per(every) + cent (100)
per cent = per 100
percentage calculation formula (%) = (part / whole ) ×100
percentage increase equation = 100 ×( final - initial) /initial
ex1 : 2% is 2 percent = 2/100 =2:100
ex2: 35% = 35/100
48% = 48/100
ex3 : find the following 10% of 25,000
step 1 : convert 10% into fraction = 10/100
step 2 : multiply the fraction with value = 10/100× 25,000
answer = 2,500
ex4 : what is 7% of 68m ?
step 1 : convert 7% into fraction = 7/100
step 2 : multiply the fraction with value = 7/100 × 68
answer = 4.76 m
ex5 : The original price of a shirt was $10. It was decreased to $5 . What is the percent decrease of the price of this shirt?
step 1 : find the amount decreased = $10–$5 =$5
step 2 : write as part / whole = $5 / $10 = $0.5
step 3 : multiply by 100 = 0.5 × 100 = 50%
ex6 : Mary has a monthly salary of $21,000. She spends $350 per month on food. What percent of her monthly salary does she spend on food?
step 1 : write as part /whole and multiply by 100
= ( 350 / 21000 ) ×100 = 1.7 %
ex6 : The price of a pair of shoes was decreased by 21% to $100. What was the original price of the trousers?
step 1 : write % as fraction = 21/100
original price = y
(y × 21/100 ) = amount decreased --------- 1
y - amount decreased = $100 -------------- 2
rearrange equation 2 as;
y - $100 = amount decreased -------------- 3
when you equate both equation 1 and 3 you should get the ans y = $ 126.58
ex6 : The price of an item changed from $120 to $100. Then later the price decreased again from $100 to $80. Which of the two decreases was larger in percentage term?
step 1 : part / whole = (120 - 100) / 120 = 0.17 = 17%
step 2 : part / whole = (100 - 80) / 100 = 0.20 = 20%
The part were the same in both cases but the whole was smaller in the second decrease.
ex7 : A family had dinner in a restaurant and paid $35 for food. They also had to pay 9.5% sale tax and 10% for the tip. How much did they pay for the dinner?
for food = $35
sale tax = 9.5/100 × 35 = $3.33
tip = 10 /100 × 35 = 3.5
total = $45.83
ex8 : Smith invested $5000 for two years. For the first year, the rate of interest was 7% and the second year it was 8.5%. How much interest did he earn at the end of the two year period?
Answer
Interest at the end of the first year
7/100 * 5000 = $350
Interest at the end of the second year
8.5/100 * (5000 + 350) = $454.75
Total interest at the end of the two year period is
$350 + $454.75 = $804.75