Question

Suppose y is directly proportional to x and y=40 when x=10 find y if x=16

Answer 1

64

Explanation:

16/10=1.6 and 1.6x40=64

Answer 2

Answer: y = 64

Explanation:

`$$Given, \\$y$ is directly proportional to $x$ \\$\Rightarrow y \propto x$ (Note: ' $\alpha$ ' be proportion/various sign) \\$\Rightarrow y=k x$ ( $k$ be the constant) \\$\therefore y=k x-$ (1)`

`$$Given $y=40$ when $x=10$.So, substitute $y=40 \ \& \ x=10$ in (1) we get,$$\begin{aligned}&\Rightarrow 40=k(10) \\&\Rightarrow 10 k=40 \\&\Rightarrow k=(40)/(10) \text { (divide '10' both sides) } \\&\Rightarrow k=4\end{aligned}$$`

`$$Put $k=4$ in (1) we get,$$y=4 x$$We substitute $x=16$ in (2) we get$$\begin{aligned}y &=4(16) \\\Rightarrow y &=64 \\\end{aligned}$$`