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Finding the Fourth Proportional to 86.81, 129.90 and 66.35

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Solution

The fourth proportional to 86.81, 129.90 and 66.35 is: 99.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.81 : 129.90 = 66.35 : x
  2. Step 2: Convert to fraction form
    86.81/129.90 = 66.35/x
  3. Step 3: Cross multiply
    86.81x = 129.90 × 66.35
  4. Step 4: Simplify right side
    86.81x = 8,619.44
  5. Step 5: Solve for x
    x = 8,619.44/86.81
  6. Step 6: Final answer
    x = 99.30

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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.