Week 3:

Due Tuesday, September 4 : Hand in: (typed! but equations, diagrams etc may be put in by hand) (1) Write a ratio problem that can be solved with the aid of a strip diagram. Explain clearly how to solve the problem (use this opportunity to help you really think through and make sense of the ideas!). (2) An aquarium contained an equal number of horseshoe crabs and sea stars. After 15 horseshoe crabs were removed and 27 sea stars were removed, the ratio of horseshoe crabs to sea stars was 5 : 3. How many horseshoe crabs and sea stars were there at first? Explain how to solve this problem in two ways: with the aid of a strip diagram and by setting up and solving an equation.

Due Thursday, September 6 : Hand in: (typed! but equations, tables, graphs etc may be put in by hand): (1) Problem 23 on page 314. (2) (counts as 3 problems) (a) Make up two situations, one in which two varying quantities are directly proportional and one in which two varying quantities are inversely proportional. In each case, let x, y stand for the amounts of the two quantities (your "quantities" don't have to be physical objects, they could include such things as elapsed time or speed -- things that are measurable). (b) In each case, make a table showing some values for x and y, write an equation that relates x and y, and sketch a graph of y as a function of x. (c) In each case, discuss how y changes as x increases: say why that way of changing makes sense logically in terms of the situation and say how you can see the way y changes as x increases reflected in the table, in the equation, and in the graph.

Week 4:

Due Tuesday, September 11: QUIZ on ratio and proportion (direct proportion only). Read section 13.2 and do the practice problems.

MATH 7020 students only: Extra Assignment 1

Due Thursday, September 13: Read section 13.1 and do the practice problems. Hand in: (typed OR a neatly written 2nd (or later) draft): Problems 11, 22 on page 607, 608. For #22, explain how to solve in two ways: with a strip diagram and with equations. Also hand in: (1) Write a story problem that can be solved by solving the equation (3/4)x=39 and that can also be solved with a strip diagram. Explain how to solve the problem with the strip diagram. Then explain how you can use the strip diagram solution method to explain why we can solve the equation above by multiplying 39 by 4/3 (in other words, explain why it makes sense that 39 divided by 3/4 is equivalent to 39 times 4/3, the reciprocal of 3/4).