#adv.

AB, CD and GH are straight lines with AB and CD parallel. see the figure The two marked angles are:

• alternate

• co-interior

• corresponding

• exterior

In the diagram, AB ||CD. In this case, find the value of a and give your reason or reasons.

Carl has drawn straight lines from B to C and from A to C to form the triangles BOC and AOC. He knows that OC is 25 cm long, and he measures the line AC to be 43.3 cm long. If using string to form the two smaller triangles in the diagram (without forming OC twice), how much string will Carl need?

• 100. 100.3cm

• 125.3 cm

• 140.3 cm

• 143.3 cm

Five is added to each store in a data set. What effect will this have on the mean and the standard deviation?

• Mean stays the same, standard deviation stays the same

• mean goes up by 5: standard deviation stays the same

• mean stays the same: standard deviation goes up by 5

• mean goes up by 5: standard deviation goes up by 5

• 55

• 80

• 95

• 100

Peter is analyzing the set of six scores shown, expressed in terms of a number x : x - 1, x - 1, x - 1, x, x, x. Which of the following must be true for the set of scores?

• mean < median

• median < mean

• mean = median

• median = range

One-third of the water in a leaking tank at the start of each hour is lost in that hour. This means that one hour after containing 270 liters, 180 liters remained in the tank. How many liters will be in the tank after an additional two hours?

• 60

• 80

• 90

• 120

John is using a crane to stack concrete slabs measuring 2 meters x 1 meter x 0. 3 meters. He is arranging the slabs in 5 layers of 24 to form a rectangular prism with a finished height of 1.5 meters. If the concrete in the slabs weighs 2000 kilograms per cubic meter, how many tonnes will the finished stack weight?

• 144

• 240

• 144 000

• 240 000

• I and II

• III and IV

• I only

• III only