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Finding the Fourth Proportional to 91.46, 136.45 and 86.90

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Solution

The fourth proportional to 91.46, 136.45 and 86.90 is: 129.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.46 : 136.45 = 86.90 : x
  2. Step 2: Convert to fraction form
    91.46/136.45 = 86.90/x
  3. Step 3: Cross multiply
    91.46x = 136.45 × 86.90
  4. Step 4: Simplify right side
    91.46x = 11,857.51
  5. Step 5: Solve for x
    x = 11,857.51/91.46
  6. Step 6: Final answer
    x = 129.65

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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.