Further Mathematics Paper 2, Nov/Dec. 2011
 Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Main
Weakness/Remedies
Strength
Question 6
1. In a physics examination, the mean mark of the first twelve students in a class is 60, that of the next twenty students is 50 and that of the remaining y students is x. What is the mean mark for the whole class in the examination, in terms of x and y.
2. A box contains 4 red and 3 blue identical balls. If two balls are picked at random, one after the other without replacement, find the probability that one is red and the other blue.

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Observation

The report stated that this question was attempted by majority of the candidates and their performance was commended. Majority of them were reported to have earned full marks.
In part (a), candidates were able to obtain the total number of students to be equal to 12 + 20 + y = 32 + y. The total mark for the students was (12 x 60) + (20 x 50) + xy = 1720 + xy. Hence the mean mark for the class was .
In part (b), candidates were able to show that P(one red and the other blue) = P(1st is red and 2nd blue or 1st is blue and 2nd red) = () + () =  or 0.57.