+1641 2/9 of the pupils in Primary 5 scored an 'A' for a test. The ratio of the number of pupils who scored a 'B' to the number who scored an 'A' was 5 : 3. The rest of the pupils scored a 'C' and a 'D' in the ratio of 6 : 5. The pupils who scored a 'B' were 48 more than the pupils who scored a 'C'.
(a) How many pupils were there in Primary 5?
(b) How many pupils failed the test if the failure was a 'D' grade?
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A = 2/9 A = 6/27
A : B = 3 : 5 A + B = 16/27
3/5 = (6/27) / B B = 10/27
C + D = 11/27 C = 6/27
C : D = 6 : 5
D = 5/27
B / C = 5 / 3
5 / 3 = (48 + C) / C C = 72
B = 48 + C B = 120
C / D = 6 / 5 D = 60
A = 72
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Total = 324
Ratio: A : B : C : D = 6 : 10 : 6 : 5
