When a certain tree was first planted, it was 4 feet tall, and the heigth 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 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increased each year?
+128406 Let m be the constant amount (in feet) that it grows every year....so.....at the end of 4 years, the height is
[4 + 4m]
And at the end of the 6th year the height is 4 + 6m
And we know that
(1 + 1/5) [ 4 + 4m ] = 4 + 6m
(1.2) [ 4 + 4m ] = 4 + 6m
4.8 + 4.8m = 4 + 6m
4.8 - 4 = 6m - 4.8m
.8 = 1.2m divide both sides by 1.2
.8 / 1.2 = m = 8/12 = 2/3 ft = 8 inches per year
