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Finding the Fourth Proportional to 861.60, 1,291.28 and 445.28

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Solution

The fourth proportional to 861.60, 1,291.28 and 445.28 is: 667.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.60 : 1,291.28 = 445.28 : x
  2. Step 2: Convert to fraction form
    861.60/1,291.28 = 445.28/x
  3. Step 3: Cross multiply
    861.60x = 1,291.28 × 445.28
  4. Step 4: Simplify right side
    861.60x = 574,981.16
  5. Step 5: Solve for x
    x = 574,981.16/861.60
  6. Step 6: Final answer
    x = 667.34

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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.