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Finding the Fourth Proportional to 870.40, 1,305.37 and 431.40

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Solution

The fourth proportional to 870.40, 1,305.37 and 431.40 is: 646.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.40 : 1,305.37 = 431.40 : x
  2. Step 2: Convert to fraction form
    870.40/1,305.37 = 431.40/x
  3. Step 3: Cross multiply
    870.40x = 1,305.37 × 431.40
  4. Step 4: Simplify right side
    870.40x = 563,135.95
  5. Step 5: Solve for x
    x = 563,135.95/870.40
  6. Step 6: Final answer
    x = 646.99

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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.