Question

A seed sprouted and grew
2
3
of a foot in 3 months. What was its rate of growth?

Answer 1

I will assume you are trying to say:
"A seed sprouted and grew 2/3 of a foot in 3 months"

so in one month it would grow (2/3) ÷ 3 or 2/9 of a foot in 1 months

average rate of growth = 2/9 ft/month

Answer 2

1.14