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Finding the Fourth Proportional to 103.90, 155.91 and 71.42

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Solution

The fourth proportional to 103.90, 155.91 and 71.42 is: 107.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.90 : 155.91 = 71.42 : x
  2. Step 2: Convert to fraction form
    103.90/155.91 = 71.42/x
  3. Step 3: Cross multiply
    103.90x = 155.91 × 71.42
  4. Step 4: Simplify right side
    103.90x = 11,134.18
  5. Step 5: Solve for x
    x = 11,134.18/103.90
  6. Step 6: Final answer
    x = 107.16

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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.