Ques: 1. In an examination 72% of the candidates passed and 280 failed, then find the total number of candidates.
Solution: Assume that 100 candidate took the examination.
In that 72% of them are passed =72 candidates
In that failed candidates =(100−72)=28
Number of candidates if 28 of them failed =100
Number of candidates if 280 of them failed =(100/28)×280
=1000
∴ the total number of examinees is 1000
Ques: 2. 60% of the population of a city is male. If the total population of that city is 40,000, then what will be the number of females?
Solution: Given:
Male percent in city = 60%
Total population of the city = 40,000
Calculation:
Total male in city = 40,000 × (60/100) = 24,000
Total male in city = 40,000 – 24,000 = 16,000
∴ Total male in the city is 34,800
Ques: 3. If the side of a square is decreased by 20%, then by what % will its area decrease?
Solution:
Given,
Decrease percent = 20%
Concept used:
Using the concept of percentage
Area of square = (Side)²
Calculation:
Let the original side be 20
Area of original square = (Side)²
⇒ Original area = 400
New side = (100 – 20)% of 20
⇒ New side = 80/100 × 12
⇒ New side = 16
New area = (New side)2
⇒ New area = (16)2
⇒ New area = 256
Percent decrease in area = (Original area – New area)/(Original area) × 100
⇒ Percent decrease in area = (400-256)/400 × 100
⇒ Percent decrease in area = 36%
∴ The percentage decrease in area is 36%.
Ques: 4. The salary of 'A' is 50% more than that of 'B'. If the salary of 'A' is Rs.4500. What will be the salary of 'B'?
Solution: Given,
Salary of A is Rs. 4500
Salary of A is 50% more than B i.e.,
Salary of B= x Rs.
According to ques, A= B+B(50%)
4500= x + x* 50/100
4500= 3/2x
x= 4500* 2/3
x = 3000 Rs.
∴ Therefore, salary of B is 3000 Rs.
Ques: 5. If the price of a car increased from Rs. 50,000 to Rs. 60,000, then what was the percentage increase in the price?
Solution: Price of car is 50,000
Increased price of car is 60,000
Difference 60,000-50,000= 10,000
According to concept,
=> 10,000/50,000*100
=> 20%
∴ Therefore, percentage increase in the price is 20%.
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