## Sunday, April 11, 2010

### Gordon's Fraction Growing Post

I could not locate my ustream test video even tho I looked through both accounts thoroughly.

Question 1: Explain how to multiply a fraction by a whole number.
I'll use 4/5 x 3 = 12/5 or 2 2/5
Now to multiply a fraction by a whole number is simple all you do is multiply the numerator (top number) by the number you are multiplying (in this case 3) so when you see 4/5 x 3 you should think 4 x 3 = 12 then simply replace the denominator (bottom number) so you'll get 12/5. Another way is to convert the whole number into a fraction by simply placing a 1 under the whole number so 3 would become 3/1 so 4/5 x 3 becomes 4/5 x 3/1 and when multiplying two fractions you multiply the numerator by the numerator and the denominator by the denominator so you end up with
4 x 3 = 12
5 x 1 = 5
so you get 12/5 but we must convert this improper fraction to a mixed fraction so we must find out how many times 5 goes into 12 it goes into 12 2 times with a remainder of 2 so we get 2 2/5.

Question 2: Explain how to divide a fraction by a whole number.
1/4 ÷ 2 = 1/8

Begin by drawing the fraction

Next Divided the picture by the whole number

= 1/8

Question 3: Solve one word problem of your choice from the questions 6-12 on page 208 of the textbook
Mark uses 1/3 of a tank of gasoline in a five-day work week driving to work and back. On average, what fraction of a tank does he use for each round trip?
The question is essentially asking what is 1/3 ÷ 5? so I'll use the method I explained earlier

= 1/15

1/4 x 1/4 = 1/16
1 x 1 = 1
4 x 4 = 16

1/3 x 2 2/4 = 10/12
2 2/4 = 10/4
1/3 x 10/4 = 10/12
1 x 10 = 10
3 x 4 = 12

1 2/3 x 2 1/5 = 55/15
1 2/3 = 5/3
2 1/5 = 11/5
5/3 x 11/5 =55/15
5 x 11 = 55
3 x 5 = 15

1 1/2 ÷ 3/4 =
1 1/2 = 3/2
3/2 ÷ 3/4 =
So what you have to do is figure out how many times 3/4 goes into 3/2 but to do that we need to find the lowest common denominator.
1/2 = 2/4
3/2 = 6/4
And 3/4 goes into 6/4 two times
And so the answer is 1 1/2 ÷ 3/4 = 2

3/4 ÷ 1/2 =
Find the lowest common denominator
1/2 = 2/4
So the question becomes 3/4 ÷ 2/4 =
And 2/4 goes into 3/4, 1 1/2 times.
And so the answer is 3/4 ÷ 2/4 = 1 1/2

#### 1 comment:

1. Good job explaining everything, and good job with the pictures.