Inverse proportionality is exactly opposite to directly proportions i.e. two variables are said to be inversely proportional if an increase in value of one variable results in a decrease in value of the other variable and similarly a decrease in value of one variable results in an increase in value of the other variable. The questions are also of the form, "If x results in a, what will be the result if x changes to y?
question 1. A car takes 1 hour and 30 minutes to travel the distance between two cities during rush hour. If the average speed is 50% more during off-peak hours, what time will it take to cover the same distance between the two cities during off peak hours (1 hour = 60 minutes)?
(a) 45 Minutes (b) 1 Hour (c) 1 Hour 15 Minutes
(d) 90 Minutes (e) 1 Hour 45 minutes
Solution: Step 1: The time taken to cover the distance and the speed are inversely proportional. Let the speed during rush hour be 8.
The average speed is 50% more during off-peak hours therefore off-peak hour speed = 1.5s
Step 2: With speed s it takes 1 hour 30 minutes = 1 × 60 + 30 = 90 minutes
Since the speed and time are inversely proportional, the time taken with speed Minutes or 1 Hour
The correct answer is B
CBSE NCERT Solutions for Class 8 Maths
class 8 maths NCERT solutions Chapter 1: Rational Numbers
class 8 maths NCERT solutions Chapter 2: Linear Equations in One Variable
class 8 maths NCERT solutions Chapter 3: Understanding Quadrilaterals
class 8 maths NCERT solutions Chapter 4: Practical Geometry
class 8 maths NCERT solutions Chapter 5: Data Handling
class 8 maths NCERT solutions Chapter 6: Square and Square Roots
class 8 maths NCERT solutions Chapter 7: Cube and Cube Roots
class 8 maths NCERT solutions Chapter 8: Comparing Quantities
NCERT Class 8 Maths solution Chapter 9: Algebraic Expressions and Identities
class 8 maths NCERT solutions Chapter 10: Visualizing Solid Shapes
class 8 maths NCERT solutions Chapter 11: Mensuration
class 8 maths NCERT solutions Chapter 12: Exponents and Powers
class 8 maths NCERT solutions Chapter 13: Direct and Inverse Proportions
class 8 maths NCERT solutions Chapter 14: Factorization
class 8 maths NCERT solutions Chapter 15: Introduction to Graphs
class 8 maths NCERT solutions Chapter 16: Playing with Numbers
Notes,worksheet and solved question for Maths class 8
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