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Finding the Fourth Proportional to 855.12, 1,282.68 and 685.20

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Solution

The fourth proportional to 855.12, 1,282.68 and 685.20 is: 1,027.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    855.12 : 1,282.68 = 685.20 : x
  2. Step 2: Convert to fraction form
    855.12/1,282.68 = 685.20/x
  3. Step 3: Cross multiply
    855.12x = 1,282.68 × 685.20
  4. Step 4: Simplify right side
    855.12x = 878,892.34
  5. Step 5: Solve for x
    x = 878,892.34/855.12
  6. Step 6: Final answer
    x = 1,027.80

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.