1. you can do 90 sit-ups in 2 minutes. your friend can do 135 sit-ups in 3 minutes. do these rates form a proportion? explain
2. the ratio of quarters to dimes in a coin collection is 5: 3. you add the same number of new quarters as dimes to the collection.
a. is the ratio of quarters to dimes still 5: 3?
b. if so, illustrate with an example. if not, give a counter-example.
3. you are 13 years old, and your cousin is 19 years old. as you grow older, is your age proportional to your cousin's age? explain your reasoning