Question

The owner of a plant nursery wanted to test the effectiveness of a new type of fertilizer. He measured the heights of $5$ plants, and then gave each an equal amount of fertilizer. Two weeks later, he measured the heights of the plants again. The graph shows the height of the plants before and after the addition of fertilizer.
What was the mean growth of the plants?

• A. $4.5$cm
• B. $5$cm
• C. $5.5$cm
• D. $6$cm

Answer 1

The correct option is A $4.5$cm

The growth of plant $=$height after addition of fertilizer$-$ height before fertilizer.

$\therefore$ plant 1 growth$=17-12.5=4.5cm$

Similarly, $4cm,4cm,4.5cm$ and $5.5$ are growths of plant 2, 3, 4 and 5 respectively.

$\therefore$ Mean growth $=\frac{4.5+4+4+4.5+5.5}{5}=\frac{22.5}{5}=4.5cm$