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Finding the Fourth Proportional to 91.76, 136.90 and 87.68

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Solution

The fourth proportional to 91.76, 136.90 and 87.68 is: 130.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.76 : 136.90 = 87.68 : x
  2. Step 2: Convert to fraction form
    91.76/136.90 = 87.68/x
  3. Step 3: Cross multiply
    91.76x = 136.90 × 87.68
  4. Step 4: Simplify right side
    91.76x = 12,003.39
  5. Step 5: Solve for x
    x = 12,003.39/91.76
  6. Step 6: Final answer
    x = 130.81

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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.