Question

If x varies directly as y and x = 9 when y = 25, what is the value of y when

x = 45?​

Answer 1

Answer:

According to the question given x varies directly as y

This can be written as:

x ∝ y

⇒ x = ky  (where k is a constant) ----- Equation 1

Now given when y = 25, then x = 9

Substituting the values of x and y in Equation 1

⇒ x = ky

⇒ 9 = k × 25

⇒ 9/25 = k

or  k = 9/25

Now we have to find the value of y when x  = 45,

Let's input the values of x = 45 and k = 9/25 in Equation 1

x = k × y

⇒ 45 = (9/25) × y  (Substituting the values of x = 45 and k = 9/25)

⇒ (45 × 25)/9 = y

or y = (45 × 25)/9

or y = (5 × 9 × 25)/9  (45 = 5 × 9, ∴ In RHS, 9 can be can cancelled from the Numerator and the Denominator)

or y = (5 × 25)  

or y = 125  

So, when x = 45, y = 125 (Ans)

Step-by-step explanation: