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Ratios, Percentages, and Proportions Videos 55 videos
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ACT Math 5.5 Pre-Algebra 347 Views
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Description:
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?
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...
Full Transcript
- 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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