Question

If a pine tree grows 4 inches per year, how long will it take for the tree to reach a height of 13 feet?

Answer 1

39 yr

Explanation:

Convert "4 inches per year" to "feet per year:"

4 inches 1 ft

-------------- * --------- = (1/3) ft/yr

1 year 12 in

Now we know the growth rate. The time required to reach a certain height is

3 yr

-------- * 13 ft = 39 yr

1 ft

Answer 2

Should be 39 years.

there is 12 inches in a foot. and if the tree grows 4 inches every year, then in 3 years the tree would be 1 foot. 13 x 3 = 39, thus proving that in 39 years, it will be 13 feet tall. I may be wrong but this sounds correct.