Question

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Answer 1

Qᴜᴇsᴛɪᴏɴ :-

• if x varies directly as y and x = 0.75 when y = 5. find x when y = 21 ?

Sᴏʟᴜᴛɪᴏɴ :-

Varies Directly :- Also Known as Directly proportional , that Means, as one amount increases, another amount also increases at the same rate.

→ x ∝ y

→ x = ky ( where k is any constant Number ).

So,

→ 0.75 = k * 5

→ k = 0.75/5

→ k = 0.15 .

Therefore , when y = 21 .

→ x = k * y

→ x = (0.15) * 21

→ x = 3.15 (Ans.)

Hence, value of x will be 3.15 when y is 21.

Answer 2

QuEsTiOn:

• If x varies directly as y and x = 0.75 when y = 5, find x when y = 21

SolutiOn:

Varies directly : Varies directly means Both are directly proportional to each other

Directly proportional : Suppose taking two properties x & y . If x increases 10 times then y also increases 10 times

Denoted by : x $\propto$ y

Removing proportionality. We get a constant k

$\to$ x = ky

Substituting value of x & y

$\to$ 0.75 = k × 5

$\to$ k = 0.75/5

$\to$ k = 0.15

Substituting y = 21 & k = 0.15

$\to$ x = (0.15)(21)

$\to$ x = 3.15

$\therefore$ Value of x = 3.15 when y = 21