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Finding the Fourth Proportional to 92.90, 138.58 and 86.35

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Solution

The fourth proportional to 92.90, 138.58 and 86.35 is: 128.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.90 : 138.58 = 86.35 : x
  2. Step 2: Convert to fraction form
    92.90/138.58 = 86.35/x
  3. Step 3: Cross multiply
    92.90x = 138.58 × 86.35
  4. Step 4: Simplify right side
    92.90x = 11,966.38
  5. Step 5: Solve for x
    x = 11,966.38/92.90
  6. Step 6: Final answer
    x = 128.81

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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.