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Finding the Fourth Proportional to 90.55, 135.78 and 39.18

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Solution

The fourth proportional to 90.55, 135.78 and 39.18 is: 58.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.55 : 135.78 = 39.18 : x
  2. Step 2: Convert to fraction form
    90.55/135.78 = 39.18/x
  3. Step 3: Cross multiply
    90.55x = 135.78 × 39.18
  4. Step 4: Simplify right side
    90.55x = 5,319.86
  5. Step 5: Solve for x
    x = 5,319.86/90.55
  6. Step 6: Final answer
    x = 58.75

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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.