Saturday, September 11, 2010

Ratio P6 2010 SA2 CHIJ P2 Q17

There were a total of 480 pink and black pearls in a box. The number of pink pearls was 1½ times that of black pearls. Some silver pearls and some white pearls were put into the box. For every 6 pink pearls that were already in the box, 13 white ones were added. Then the final number of black peals and silver pearls was 25% of the final number of pink pearls and white pearls. What is the ratio of the number of silver pearls to the number of white ones? [5 marks][Answer given: 3: 52]


5 u --> 480
1 u --> 480/5 = 96

P : 3 u --> 3 x 96 = 288

B --> 480 - 288 = 192

W --> 288/6 x 13 = 624

P + W --> 288 + 624 = 912

B + S --> 25/100 x 912 = 228

S --> 228 - 192 = 36

S : W = 36 : 624
         = 3 : 52

It was 3 : 52.

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