Chapter 7: Q.502. (page 742)

If $y$ varies directly with $x$ , and $x = 5$ when $y = 30$ , find $x$ when $y = 42$ .

Short Answer

Expert verified

The solution is $x = 7$ .

Step by step solution

Step 1. Given information.

If $y$ varies directly with $x$ , and $x = 5$ when $y = 30$ .

Step 2. Write the equation.

$y α x y = k x$

where $k$ is constant of proportionality.

Step 3. Find the value of k, when y=30 and x=5.

$y = k x 30 = k 5 k = \frac{30}{5} k = 6$

Step 4. Now, solve for x, when k=6 and y=42.

$y = k x 42 = 6 x x = \frac{42}{6} x = 7$

Step 5. Simplified answer.

Hence, the solution is $x = 7$ .

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If $y$ varies directly with $x$ , and $x = 5$ when $y = 30$ , find $x$ when $y = 42$ .

Short Answer

Step by step solution

Step 1. Given information.

Step 2. Write the equation.

Step 3. Find the value of k, when y=30 and x=5.

Step 4. Now, solve for x, when k=6 and y=42.

Step 5. Simplified answer.

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Ifyvaries directly withx, andx=5wheny=30, findxwheny=42.

Short Answer

Step by step solution

Step 1. Given information.

Step 2. Write the equation.

Step 3. Find the value of k, when y=30 and x=5.

Step 4. Now, solve for x, when k=6 and y=42.

Step 5. Simplified answer.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Geometry

Calculus

Logic and Functions

Theoretical and Mathematical Physics

Discrete Mathematics

Applied Mathematics

Study anywhere. Anytime. Across all devices.

If $y$ varies directly with $x$ , and $x = 5$ when $y = 30$ , find $x$ when $y = 42$ .