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1.
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1525535Correct!Wrong!A quarter of the balls are green, so 25 greens. There are twice as many blues as greens, so 50 blues. There are one-fifth as many reds as blues, so 10 reds. Add them together and you get 85, so the remaining 15 must be white.
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2.
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23.511.114.420Correct!Wrong!1430 - 1250 = 180. 180 ÷ 1250 = 0.144. 0.144 x 100 = 14.4.
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3.
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0.50.90.40.7Correct!Wrong!28 ÷ 40 = 0.7.
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4.
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6 red, 3 white, 1 blue5 red, 3 white, 2 blue7 red, 2 white, 1 blue8 red, 1 white, 1 blueCorrect!Wrong!You'd expect 7 out of 10 reds to give a relative frequency of 0.7.
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5.
25 : 182 : 132 : 119 : 7Correct!Wrong!You multiply the ratios together, so it's (10 x 5) : (5 :4), or 50 : 36. Then you need to see if both sides can be divided by anything to give you the simplest version. In this case, dividing them both by 2 gives you 25 : 18.
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6.
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£6,500£6,775£7,225£7,775Correct!Wrong!The way to work it out is 9,000 ÷ 1.05^3 = 7,774.54.
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7.
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YesNoCorrect!Wrong!24 ÷ 40 = 0.6, so less than 2/3rds.
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8.
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891215Correct!Wrong!There are three possible "starter and main" combinations, and six possible "main and dessert" combinations, for a total of nine.
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9.
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1/52/51/32/3Correct!Wrong!There are nine possible combinations; three of them include jelly.
So it's 3/9 or 1/3.
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10.
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591113Correct!Wrong!You know that spruce trees + pine trees + 2 = fir trees. 27 fir trees and 16 pine trees have been sold. So 27 - 26 - 2 = 9.
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11.
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4.4 x 10^54.4 x 10^64.4 x 10^84.4 x 10^523Correct!Wrong!The correct answer is 437,062, or 4.4 x 10^5.
