Question

For the following data, if X has a value of 20, what is Y'? (you can assume that a=1)

Participant	X Variable	Y Variable
1	5	2
2	10	3
3	15	4

Answer 1

Answer 2

To find $Y$ when $X=20$, we observe the linear relationship between $X$ and $Y$:

$$\begin{array}{rl}{\displaystyle \text{Slope (b)}}& {\displaystyle =\frac{\mathrm{\Delta }Y}{\mathrm{\Delta }X}=\frac{3-2}{10-5}=\frac{1}{5}=0.2}\\ {\displaystyle \text{Intercept (a)}}& {\displaystyle =1(\text{given})}\\ {\displaystyle Y}& {\displaystyle =a+bX=1+0.2\times 20=1+4=5}\end{array}$$

Answer: $Y=5$