Questions from CIE:
As part of a job interview, Iris has been given a memory test.
She was given one minute to study a picture of a clock whose numbers 1 to 12 were a variety of
colours.
At the end of the minute she was confident of the following:
• Four of the numbers were green, three were blue, three were yellow and two were red.
• The three blue numbers were 2, 7 and 12.
• Except for the two red numbers, no two neighbouring numbers were the same colour.
• No pairs of opposite numbers (12 and 6, 1 and 7 etc.) had repeated colour combinations
(so, for instance, two of the green numbers must have been opposite each other, since
green cannot have been opposite blue, red or yellow twice).
Now Iris has been asked to name the colour of each of the twelve numbers on the clock face.
The information that Iris has memorised is sufficient for her to be certain of the colour of how
many of the twelve numbers?
A Three
B Four
C Eight
D Twelve
Every month, when I pay my rent, the landlord gives me a bill for utilities. I know that all fixed
charges are included in my monthly rent, so my extra bill for each utility is calculated by
multiplying the number of units that I have used by the price per unit. I do not know which of gas,
electricity and water I am being charged for. In the last four months I have recorded the number
of units of each that I used and the amount that I was charged by the landlord.
Electricity (units) Gas (units) Water (units) Landlord’s bill ($)
50 71 32 2.77
53 71 34 2.81
50 71 28 2.69
54 74 35 2.92
What am I being charged for?
A Electricity and gas.
B Electricity and water.
C Gas and water.
D Electricity, gas and water.