Direct and inverse proportion Quiz

1. $y$ is directly proportional to $x$, and $y=12$ when $x=3$. Find $y$ when $x=7$.

• A. $21$
• B. $28$
• C. $25$
• D. $36$

2. $a$ is inversely proportional to $b$, and $a=8$ when $b=3$. Find $b$ when $a=12$.

• A. $2$
• B. $4.5$
• C. $1.5$
• D. $17$

3. Which describes the graph of $y=\frac{k}{x}$ for $x>0$?

• A. a straight line through the origin
• B. a straight line with negative gradient
• C. a curve through the origin
• D. a curve that never meets either axis

4. A recipe for $4$ people uses $300$ g of rice. How much rice is needed for $10$ people?

• A. $1200$ g
• B. $750$ g
• C. $600$ g
• D. $700$ g

5. $6$ workers finish a job in $10$ days. How long would $15$ workers take at the same rate?

• A. $25$ days
• B. $6$ days
• C. $4$ days
• D. $1.5$ days