Question

If a farmer were to calculate the height of a plant in the 5th week by finding the average growth rate, how tall would the plant be?

• A. 13.3 cm
• B. 70 cm
• C. 63.3 cm
• D. 73.3 cm

Answer 1

The correct option is D 73.3 cm

To find the average growth rate, we calculate the height the plant has grown in consecutive weeks.

$Growthfromweek1toweek2$

$=\text{Height in week 2}–\text{Height in week 1}$
$=40cm–20cm$
$=20cm$

$Growthfromweek2toweek3$

$=\text{Height in week 3}–\text{Height in week 2}$
$=50cm–40cm$
$=10cm$

$Growthfromweek3toweek4$

$=\text{Height in week 4}–\text{Height in week 3}$
$=60cm–50cm$
$=10cm$

$Averagegrowthrate=\frac{10+10+20}{3}\approx 13.3cm$

$Heightinweek5$

$=\text{Height in week 4}+\text{Average growth rate}$
$=60cm+13.3cm$
$=73.3cm$