Question

The height of a sunflower plant varies directly with its age.Once it has sprouted from the ground, when a sunflower is 2 weeks old, it is 38 centimeters tall. When it is 6 weeks old, it is 114 centimeters tall. How tall is a sunflower plant that is 3 and a half weeks old?

Answer 1

It varies directly, so the ratio of the age to the height is constant.

2 weeks old - 38 cm tall
3.5 weeks old - x cm tall


`(2)/(38)=(3.5)/(x) \\ 2x=3.5 * 38 \\ 2x=133 \\ x=66.5`

A sunflower plant that is 3 and a half weeks old is 66.5 centimeters tall.