When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of the 6th year, the tree was 1/3 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year?
Choose the correct option.
A) 3/10 B) 2 C) 1/2 D) 2/3 E) 6/5
Say, the tree grows by x feet every year.   Then, 4 + 6x = (1+1/3)(4+4x)   or, x = 2   Answer 2
<result>B</result>
When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of the 6th year, the tree was 1/3 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year?