In the figure, the feasible region (shaded) for a LPP is shown. Determine the maximum and minimum value of $Z=x+2y$.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Max: 9, Min: $\frac{12}{7}$
Here, corner points are given as follows:
$R\left(\frac{7}{2}, \frac{3}{4}\right), Q\left(\frac{3}{2}, \frac{15}{4}\right), P\left(\frac{3}{13}, \frac{24}{13}\right) \text{ and } S\left(\frac{18}{7}, \frac{2}{7}\right).$
Now, evaluating the value of $Z$ for the feasible region $RQPS$.
|
Corner points |
Value of $Z=x+2y$ |
|
$R\left(\frac{7}{2}, \frac{3}{4}\right)$ |
$Z = \frac{7}{2} + 2\left(\frac{3}{4}\right) = 5$ |
|
$Q\left(\frac{3}{2}, \frac{15}{4}\right)$ |
$Z = \frac{3}{2} + 2\left(\frac{15}{4}\right) = 9$ $\leftarrow$ Maximum |
|
$P\left(\frac{3}{13}, \frac{24}{13}\right)$ |
$Z = \frac{3}{13} + 2\left(\frac{24}{13}\right) = \frac{51}{13}$ |
|
$S\left(\frac{18}{7}, \frac{2}{7}\right)$ |
$Z = \frac{18}{7} + 2\left(\frac{2}{7}\right) = \frac{22}{7}$ $\leftarrow$ Minimum |
Hence, the maximum value of $Z$ is 9 at $\left(\frac{3}{2}, \frac{15}{4}\right)$ and the minimum value of $Z$ is $\frac{22}{7}$ at $\left(\frac{18}{7}, \frac{2}{7}\right)$.