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Finding the Fourth Proportional to 90.78, 136.09 and 56.49

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Solution

The fourth proportional to 90.78, 136.09 and 56.49 is: 84.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.78 : 136.09 = 56.49 : x
  2. Step 2: Convert to fraction form
    90.78/136.09 = 56.49/x
  3. Step 3: Cross multiply
    90.78x = 136.09 × 56.49
  4. Step 4: Simplify right side
    90.78x = 7,687.72
  5. Step 5: Solve for x
    x = 7,687.72/90.78
  6. Step 6: Final answer
    x = 84.69

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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.