Comparing Numbers

Comparing Numbers

Beginning Classwork Solve for the Variables 1. 3x = 36

2. 5x = 95

3. 7x = 128

4. 14x = 1746

A RATIO is when you compare two values using division, (like a probability) Joey pitched the ball 32 times. Of those he threw 18 strikes.

The RATIO of strikes to the total is:

18 strikes 32 thrown

=

9 strikes 16 thrown

Write the RATIO of the following situations on your classwork paper, and then reduce them to simplest form. 1. John drinks two sodas every time he eats 2 sodas three hot dogs.

3 hot dogs

3. Sandra finds 5 flowers in two hours. 5 flowers 4. Rafael travels 240 miles in 4 hours

2 hours

240 miles = 60 miles 4 hours 1hour

When you find two Ratios that are equal, it is a special time to celebrate!!!

5 flowers= 10 flowers 4 hours 2 hours 2

4

This is called a PROPORTION !!

Sometimes you will be asked if two ratios form a proportion (are equal).

3 Is equal to 8

=

3 8

15 ? 40

Sometimes, you can just reduce them compare them Yay! to They are equal!! It’s a PROPORTION!!!! PROPORTION

Then take the Sometimes it is too ridiculous to reduce “CROSS PRODUCTS” them. (multiply criss-cross)

7752 456 Is equal to 40205 2365 (x)

(7752)•(2365)

18333480

?

If they are equal, Just thenwrite it’s athem next to each other PROPORTION!!! (456)•(40205)

= 18333480

Try some on your classwork paper. Don’t hurt yourself…Use a calculator !! Are 4 and 32 equal? 16 128

Are 756 and 1428 proportional ? 1526 3008

We can also use cross products when trying to solve an equation involving ratios. Solve the Proportion: Step 1: Set your ratios (x) Step to 2: one equal Take the crossanother. products and set them equal to each other.

2 5

k = 90 = • 5k = 180

Step 3: Solve it like normal !!

Ratio Skills in The REAL WORLD!!! Joey can drive 245 miles in 3 hours. How long will it take Joey to drive 800 miles? Write

out Just compare the ratiosthe & solve!!! ratios 245 miles 3 hours

=

Now 800 miles Solve it X hours using cross products !!

Judy earns $1345 per day at her job. How long will it take Judy to earn at least $10,000 ?

Write the ratios !!