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Finding the Fourth Proportional to 91.80, 136.49 and 90.87

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Solution

The fourth proportional to 91.80, 136.49 and 90.87 is: 135.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.80 : 136.49 = 90.87 : x
  2. Step 2: Convert to fraction form
    91.80/136.49 = 90.87/x
  3. Step 3: Cross multiply
    91.80x = 136.49 × 90.87
  4. Step 4: Simplify right side
    91.80x = 12,402.85
  5. Step 5: Solve for x
    x = 12,402.85/91.80
  6. Step 6: Final answer
    x = 135.11

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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.