2.  Lesson Objective: 4.01a  Students will know how to solve word problems using slope

3.  In 2005, Joe planted a tree that was 3 feet tall. In 2010, the tree was 13 feet tall. Assuming the growth of the tree is linear, what was the rate of growth of the tree?

4.  What does “rate of growth” mean?  Slope!

5.  Remember the slope equation:  In order to find the slope we need two points

6.  In 2005, Joe planted a tree that was 3 feet tall. In 2010, the tree was 13 feet tall. Assuming the growth of the tree is linear, what was the rate of growth of the tree?  Remember, x is always years, so replace x 2 with the second year and x 1 with the first

7.  In 2005, Joe planted a tree that was 3 feet tall. In 2010, the tree was 13 feet tall. Assuming the growth of the tree is linear, what was the rate of growth of the tree?  Replace y 2 with the height from the second year and y 1 with the first

8.  Simplify the top  Simplify the bottom  Simplify the fraction to get m. Keep it as a fraction if it can’t be simplified

9.  In 2005, Joe planted a tree that was 3 feet tall. In 2010, the tree was 13 feet tall. Assuming the growth of the tree is linear, what was the rate of growth of the tree?  The slope is 2, so the tree grows 2 feet per year

10.  In 1995 a public library had 16,000 books on its shelves. In 1999 the library had 19,000 books. Assuming a linear increase, how many books were added to the library each year?

11.  We’re looking for how many for each year, usually the word “each” means slope.

12.  In 1995 a public library had 16,000 books on its shelves. In 1999 the library had 19,000 books. Assuming a linear increase, how many books were added to the library each year?  Years are always x so replace the x’s with the years  Replace the y’s with the number of books for each year

13.  Replace y 2 with 19000 and y 1 with 16000  Replace x 2 with 1999 and x 1 with 1995  Simplify the top and the bottom  Reduce the fraction

14.  In 1995 a public library had 16,000 books on its shelves. In 1999 the library had 19,000 books. Assuming a linear increase, how many books were added to the library each year?  m = 750, therefore the library adds 750 books each year

15.  Monica feeds her dog the same amount of dog food each day from a very large bag. ON the 3 rd day, she has 44 cups left in the bag, and on the 11 th day she has 28 cups left. How many cups of food does she feed her dog a day?

16.  Wendy bought a car for $25,000 and its value depreciated linearly. After 3 years the value was $21,250. What was the amount of yearly depreciation?

17.  Jamal’s parents give him $20 to spend at camp. Jamal spends the same amount of money on snacks each day. After 4 days he has $12 left. How much money is he spending each day?