The ratio 4 12 = 5 15 varies _____ with each other.

We know, Two quantities are said to be in direct proportion if with the increase or decrease of one quantity, the other quantity also increases or decreases. If x and y are in direct proportion, then x y = k ( k is any constant). The constant k is called the constant of variation. For example: Number of articles and their cost are in direct variation because as the number of articles increases, the cost also increases and vice versa. ⇒ 4 12 = 5 15 ⇒ 4 × 15 = 5 × 12 = 60 ⇒ 12 = 4 × 3 , 15 = 5 × 3 ⇒ k = 1 3 Hence, the answer is directly.

E M B I B E

Math Sight book>Chapter 7 - Commercial Mathematics>EXERCISE 7.5>Q 6

MEDIUM

8th CBSE

IMPORTANT

Earn 100

A dealer offers $20 %$ discount on the marked price of all musical instruments and still makes a profit of $25 %$ . if he gains $₹ 150$ on the sale of a harmonium, then find the marked price of the instrument.

Important Questions on Commercial Mathematics

MEDIUM

8th CBSE

IMPORTANT

Math Sight book>Chapter 7 - Commercial Mathematics>EXERCISE 7.5>Q 7

A trader offers two successive discounts of $30 %$ and $10 %$ . If he sells an article for $₹ 108$ , then find the marked price of the article.

EASY

8th CBSE

IMPORTANT

Math Sight book>Chapter 7 - Commercial Mathematics>EXERCISE 7.5>Q 8

A discount of $3 %$ is offered on the marked price of toys in a toy shop. What amount will a customer have to pay for a dancing doll marked at $₹ 1, 300$ ?

MEDIUM

8th CBSE

IMPORTANT

Math Sight book>Chapter 7 - Commercial Mathematics>Mental Maths>Q 1

If two quantities vary directly with each other, then increase in one quantity leads to the _____ in other quantity.

MEDIUM

8th CBSE

IMPORTANT

Math Sight book>Chapter 7 - Commercial Mathematics>Mental Maths>Q 2

The ratio