Y varies directly with x, and y = 15 when x = 3. What is the value of x when y = 4?

Enter your answer in the box.

Question

Mathematics

Aaden Lin

13 January, 14:00

Y varies directly with x, and y = 15 when x = 3. What is the value of x when y = 4?

Enter your answer in the box.

+1

Answers (2)

Know the Answer?

Jude Hester · Answer 1

Y varies directly as x means:

y α x

y = kx where k is constant of proportionality

y/x = k

when y = 15, x = 3, y/x = k

15/3 = k

5 = k

k = 5.

Now when y = 4, x = ?

Recall: y/x = k, k = 5

4/x = 5

5x = 4

x = 4/5

Therefore x = 4/5

I hope this explains it.

Jaelynn · Answer 2

Y = mx

15 = m (3)

m = 5

when y = 4

4 = 5 (x)

x = 0.8 or 4/5

Y varies directly with x, and y = 15 when x = 3. What is the value of x when y = 4?Enter your answer in the box.

Y varies directly with x, and y = 15 when x = 3. What is the value of x when y = 4?

Enter your answer in the box.