Kwok Homework, CVMS: 7C Math: Fraction Problem Solving

Sunday, 29 March 2020

7C Math: Fraction Problem Solving

Online math lesson: Do the work in notebook since it is difficult to write fractions on computer.
- if these questions are too hard, I will post some easier questions, still involve fractions, by the end of the week

I am sharing some of my original fraction problem solving based questions with you. Try to get the common denominator first . Will post answers in a few days. Show all steps and calculations

Example

In a forest, 2/9 of the trees are Maple, 3/7 are Oak, ¼ are Pine and the rest are Ash trees. If there are 128 Pine in the forest, how many Ash trees are there?

Step 1: common denominator for 9, 7 and 4 (denominators for all the fractions) is

9 x 7 x 4 = 252

Step 2: find the equivalent fraction for each

(multiply 4x7 = 28 to the numerator and denominator) 2/9 = 2x28 = 56; 9x28 = 252

thus, 2/9 = 56/252

Step 3: or you can also use cross multiplication to find the equivalent fraction

3/7 = A/252

A = 3 x 252 ÷ 7 = 108

1/4 = B/252

B = 252 x 1 ÷ 4 = 63

Step 4: the three fractions are 56/252 (Maple), 108/252 (Oak) and 63/252 (Pine)

Step 5: Ash tree = the rest.