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Finding the Fourth Proportional to 90.90, 136.26 and 42.78

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Solution

The fourth proportional to 90.90, 136.26 and 42.78 is: 64.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.90 : 136.26 = 42.78 : x
  2. Step 2: Convert to fraction form
    90.90/136.26 = 42.78/x
  3. Step 3: Cross multiply
    90.90x = 136.26 × 42.78
  4. Step 4: Simplify right side
    90.90x = 5,829.20
  5. Step 5: Solve for x
    x = 5,829.20/90.90
  6. Step 6: Final answer
    x = 64.13

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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.