Question

20 orange cost rs 16.80 Find the cost of 15 orange

Answer 1

Cost of 20 orange = 16.80rs.

Cost of 1 orange =

$\frac{16.80}{20} = 0.84$

Cost of 15 oranges = 0.84 × 15

Answer - 12.6 rs.

Answer 2

Answer:

Given Information:-

• Cost of 20 oranges is Ru. 16.80

*Hidden Information:-

• It is a case of direct variation as, if the quantity of oranges increase, their price (total) will also increase.

To Find:-

• Cost of 15 oranges.

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Let the cost of 15 oranges be = Rupees (x)

(SEE ATTACHMENT I)

ACCORDING TO THE QUESTION:-

$\frac{x}{y} = k \ (constant)$

(We know that in case of a direct variation, x/y = k)

$\implies \frac{16.80}{20} = \frac{x}{15}$

(In the place of,

• x, we've written the price and the place of
• y, we have written their quantity (in pieces))

$\implies \frac {1680}{20 \times 100} = \frac{x}{15}$

(As we know, 16.80 can also be written as 1680/100, we have written in that form. Denominator is provided (× 100) and from the nominator, (.) is removed)

$\implies \frac{x}{15} = \frac {1680}{20 \times 100}$

(We have now interchanged their place)

$\implies x = \frac {1680}{20 \times 100} \times 15$

(Taken denominator from LHS to RHS.

Changes:-

1/15 = 15 (After changing it's place))

$\implies x = \frac {\cancel{1680}}{\cancel{20}} \times {\cancel{100}} \times {\cancel{15}}$

(Cancelled numbers)

(See attachment II for more details)

$\implies x = 4.2 \times 3$

(After cancellation)

$\boxed{\green{\implies x = 12.6}}$

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REQUIRED ANSWER:-

$\therefore$ Cost of 15 oranges is Rupees 12.6.

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ᴛʜᴇᴀssᴀssɪɴ's BRAIN BOOSTER:-

• Know more about indirect variation.
• This variation is taken when, x and y vary indirectly.
• That means, the equation will become $xy = k \ (constant)$.