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Finding the Fourth Proportional to 90.75, 136.15 and 47.42

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Solution

The fourth proportional to 90.75, 136.15 and 47.42 is: 71.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.75 : 136.15 = 47.42 : x
  2. Step 2: Convert to fraction form
    90.75/136.15 = 47.42/x
  3. Step 3: Cross multiply
    90.75x = 136.15 × 47.42
  4. Step 4: Simplify right side
    90.75x = 6,456.35
  5. Step 5: Solve for x
    x = 6,456.35/90.75
  6. Step 6: Final answer
    x = 71.15

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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.