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Finding the Fourth Proportional to 90.89, 136.05 and 87.72

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Solution

The fourth proportional to 90.89, 136.05 and 87.72 is: 131.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.89 : 136.05 = 87.72 : x
  2. Step 2: Convert to fraction form
    90.89/136.05 = 87.72/x
  3. Step 3: Cross multiply
    90.89x = 136.05 × 87.72
  4. Step 4: Simplify right side
    90.89x = 11,934.31
  5. Step 5: Solve for x
    x = 11,934.31/90.89
  6. Step 6: Final answer
    x = 131.30

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.