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Finding the Fourth Proportional to 89.90, 133.88 and 86.86

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Solution

The fourth proportional to 89.90, 133.88 and 86.86 is: 129.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.90 : 133.88 = 86.86 : x
  2. Step 2: Convert to fraction form
    89.90/133.88 = 86.86/x
  3. Step 3: Cross multiply
    89.90x = 133.88 × 86.86
  4. Step 4: Simplify right side
    89.90x = 11,628.82
  5. Step 5: Solve for x
    x = 11,628.82/89.90
  6. Step 6: Final answer
    x = 129.35

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.