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Finding the Fourth Proportional to 809.10, 1,115.46 and 643.86

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Solution

The fourth proportional to 809.10, 1,115.46 and 643.86 is: 887.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.10 : 1,115.46 = 643.86 : x
  2. Step 2: Convert to fraction form
    809.10/1,115.46 = 643.86/x
  3. Step 3: Cross multiply
    809.10x = 1,115.46 × 643.86
  4. Step 4: Simplify right side
    809.10x = 718,200.08
  5. Step 5: Solve for x
    x = 718,200.08/809.10
  6. Step 6: Final answer
    x = 887.65

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.