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Finding the Fourth Proportional to 870.90, 1,305.73 and 431.61

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Solution

The fourth proportional to 870.90, 1,305.73 and 431.61 is: 647.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.90 : 1,305.73 = 431.61 : x
  2. Step 2: Convert to fraction form
    870.90/1,305.73 = 431.61/x
  3. Step 3: Cross multiply
    870.90x = 1,305.73 × 431.61
  4. Step 4: Simplify right side
    870.90x = 563,569.11
  5. Step 5: Solve for x
    x = 563,569.11/870.90
  6. Step 6: Final answer
    x = 647.11

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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.