
1.
1525535A quarter of the balls are green, so 25 greens. There are twice as many blues as greens, so 50 blues. There are onefifth as many reds as blues, so 10 reds. Add them together and you get 85, so the remaining 15 must be white.

2.
23.511.114.4201430  1250 = 180. 180 ÷ 1250 = 0.144. 0.144 x 100 = 14.4.

3.
0.50.90.40.728 ÷ 40 = 0.7.

4.
6 red, 3 white, 1 blue5 red, 3 white, 2 blue7 red, 2 white, 1 blue8 red, 1 white, 1 blueYou'd expect 7 out of 10 reds to give a relative frequency of 0.7.

5.
25 : 182 : 132 : 119 : 7You 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.

6.
£6,500£6,775£7,225£7,775The way to work it out is 9,000 ÷ 1.05^3 = 7,774.54.


7.
YesNo24 ÷ 40 = 0.6, so less than 2/3rds.

8.
891215There are three possible "starter and main" combinations, and six possible "main and dessert" combinations, for a total of nine.

9.
1/52/51/32/3There are nine possible combinations; three of them include jelly.
So it's 3/9 or 1/3.

10.
591113You know that spruce trees + pine trees + 2 = fir trees. 27 fir trees and 16 pine trees have been sold. So 27  26  2 = 9.

11.
4.4 x 10^54.4 x 10^64.4 x 10^84.4 x 10^523The correct answer is 437,062, or 4.4 x 10^5.