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Finding the Fourth Proportional to 259.64, 389.45 and 86.31

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Solution

The fourth proportional to 259.64, 389.45 and 86.31 is: 129.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.64 : 389.45 = 86.31 : x
  2. Step 2: Convert to fraction form
    259.64/389.45 = 86.31/x
  3. Step 3: Cross multiply
    259.64x = 389.45 × 86.31
  4. Step 4: Simplify right side
    259.64x = 33,613.43
  5. Step 5: Solve for x
    x = 33,613.43/259.64
  6. Step 6: Final answer
    x = 129.46

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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.