Thursday, September 9, 2010

Average P6 2010 SA2 HHK P2 Q17

The average length of 6 ropes was 80 cm. The average length of 4 of the ropes A,B, C and D was 15 cm more than the average length of the remaining 2 ropes E and F. (a) Find the average length of ropes E and F. Give your answer in metres. (b) If Rope E had been 18 cm shorter and Rope F had been 12 cm longer, they would have been of the same length. Find the actual length of Rope E. [5 marks][Answer given: 0.7m, 85 cm]


80 x 6 = 480

15 x 4 = 60

480 - 60 = 420

420 / 6 = 70 cm
            = 0.7 m

a) It was 0.7 m.


E [         ][    ][   18   ]      ] 70 x 2
F [         ][12]                   ] = 140 cm

2 u --> 140 - 12 - 18 = 110
1 u --> 110/2 = 55

55 + 12 + 18 = 85 cm

b) It was 85 cm.

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