## Friday, September 17, 2010

### Math problems of the week: 5th grade Trailblazers vs. Singapore Math

I. From the final word problems in the "Adding and Subtracting Fractions" chapter of the 5th grade Math Trailblazers Student Guide, p. 184:

Shannon's mother spends 1/3 of her monthly salary on rent (which includes heat). Groceries for the month and her car payment add up to about 2/5 of her salary.

A. Do these bills account for about 1/2 of her salary, more than 1/2 of her salary, or all of her salary (1 whole salary)?

B. What fraction of her salary is spent after paying for rent, groceries and her car?

II. From the final word problems in the "Fractions" chapter of the 5th grade Singapore Math Primary Mathematics 5A workbook, p. 75:

Larry spent 1/2 of his his money on a camera and another 1/8 on a radio. The camera cost \$120 more than the radio. How much money did he have at first?

III. Extra Credit:

A. In which problem set does a greater fraction of the challenge involve mathematical reasoning, and in which problem set does a greater fraction of the challenge involve reading comprehension?

B. Which skill is "higher level": mathematical reasoning, or reading comprehension?

Anonymous said...

"What fraction of her salary is spent after paying for rent, groceries and her car?"

Huh? Is that what it actually says? not "What fraction of her salary is left ...." Because there is not enough information to answer the question asked.

Because to know what fraction is spent after paying for rent, groceries and car, wouldn't se need to know how much is spent? Spending doesn't have to equal salary if you save (spending < 100% of salary) or use credit (spending > 100% of salary) Am I missing something?

Anonymous said...

You already know how much was spent on rent groceries and her car: 1/3. Add that to 2/5 her salary, but first look for a common denominator and add those two fractions. 1/3 becomes 5/15. 2/5 becomes 4/15. Add those two and you have 9/15 which is 0.6.