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Proportions Videos 8 videos

Solving Proportions Using Cross Products
6802 Views

This video covers how to use cross products to solve for a missing number in a proportion by setting that proportion with a variable over the produ...

ACT Math 1.2 Pre-Algebra
891 Views

ACT Math: Pre-Algebra Drill 1.2. What proportion of Jenna's day is spent Wii-swimming?

ACT Math 5.5 Pre-Algebra
347 Views

ACT Math: Pre-Algebra Drill 5, Problem 5. How many red cards must be added so that the proportion of red cards is one half?

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ACT Math 5.5 Pre-Algebra 347 Views


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ACT Math: Pre-Algebra Drill 5, Problem 5. How many red cards must be added so that the proportion of red cards is one half?

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English Language

Transcript

00:03

Here's your shmoop du jour:

00:05

A box of cards contains 23 red and 30 black cards. Must have been made in China.

00:10

How many red cards must be added so that the

00:13

proportion of red cards is 1/2?

00:16

And here are the potential answers...

00:22

So... we're not dealing with a standard deck of playing cards. Kind of hard to play

00:25

"Go Fish" with only one eight.

00:27

Okay, so here's a scale: 23 cards on the left -- red ones; 30 cards on the right -- black ones.

00:34

To get the red cards to be half of the total, or equal to the black cards...

00:39

...we need to have just as many of them as we have black cards.

00:43

We can just add 7 of 'em, and then we'll have 30 of each.

00:47

And that's all there is to it. Answer: D.

00:49

As in, "Deck of Card."

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