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Australian AMC 2009 - Senior Question 6

AMC AUSTRALIA · Australian AMC 2009 - Senior

Question 6

On a string of beads, the largest bead is in the centre and the smallest beads are on the ends. The size of the beads increases from the ends to the centre as shown in the diagram.

Question illustration

The smallest beads cost \$1 each, the next smallest beads cost \$2 each, the next smallest \$3 each, and so on. How much change from \$200 would there be for the beads on a string with 25 such beads?
  1. \$25
  2. \$31
  3. \$40
  4. \$52
  5. \$55