SOLUTION: 1a box contains 7 greens & 9 blue marbles.after adding some red marbles to be box,35% of the marbles are green.how many red marbles are added? 2. How many narbles must now be draw

Question 1020945: 1a box contains 7 greens & 9 blue marbles.after adding some red marbles to be box,35% of the marbles are green.how many red marbles are added?
2. How many narbles must now be drawn from the box so that you are sure to get 2 of each colour?
Thanks
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
1) let x be total marbles in the box, then
0.35 * x = 7
x = 7 / 0.35 = 20
There are 20 marbles in the box
7 + 9 + r = 20 where r is the number of red marbles
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therefore there are 4 red marbles added to the box
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2) you would have to draw 18 marbles to be sure you get two of each color
:
: reasoning is you could draw all the green and blue marbles before drawing 2 red marbles, therefore to be sure 7 + 9 + 2 = 18

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