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Finding the Fourth Proportional to 855.40, 1,284.55 and 811.56

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Solution

The fourth proportional to 855.40, 1,284.55 and 811.56 is: 1,218.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    855.40 : 1,284.55 = 811.56 : x
  2. Step 2: Convert to fraction form
    855.40/1,284.55 = 811.56/x
  3. Step 3: Cross multiply
    855.40x = 1,284.55 × 811.56
  4. Step 4: Simplify right side
    855.40x = 1,042,489.40
  5. Step 5: Solve for x
    x = 1,042,489.40/855.40
  6. Step 6: Final answer
    x = 1,218.72

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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.