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Finding the Fourth Proportional to 216.69, 324.81 and 86.66

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Solution

The fourth proportional to 216.69, 324.81 and 86.66 is: 129.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.69 : 324.81 = 86.66 : x
  2. Step 2: Convert to fraction form
    216.69/324.81 = 86.66/x
  3. Step 3: Cross multiply
    216.69x = 324.81 × 86.66
  4. Step 4: Simplify right side
    216.69x = 28,146.41
  5. Step 5: Solve for x
    x = 28,146.41/216.69
  6. Step 6: Final answer
    x = 129.89

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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.