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Finding the Fourth Proportional to 80.90, 121.28 and 42.36

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Solution

The fourth proportional to 80.90, 121.28 and 42.36 is: 63.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.90 : 121.28 = 42.36 : x
  2. Step 2: Convert to fraction form
    80.90/121.28 = 42.36/x
  3. Step 3: Cross multiply
    80.90x = 121.28 × 42.36
  4. Step 4: Simplify right side
    80.90x = 5,136.75
  5. Step 5: Solve for x
    x = 5,136.75/80.90
  6. Step 6: Final answer
    x = 63.50

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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.