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Finding the Fourth Proportional to 86.71, 129.91 and 56.28

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Solution

The fourth proportional to 86.71, 129.91 and 56.28 is: 84.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.71 : 129.91 = 56.28 : x
  2. Step 2: Convert to fraction form
    86.71/129.91 = 56.28/x
  3. Step 3: Cross multiply
    86.71x = 129.91 × 56.28
  4. Step 4: Simplify right side
    86.71x = 7,311.33
  5. Step 5: Solve for x
    x = 7,311.33/86.71
  6. Step 6: Final answer
    x = 84.32

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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.