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Finding the Fourth Proportional to 142.78, 213.66 and 91.42

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Solution

The fourth proportional to 142.78, 213.66 and 91.42 is: 136.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.78 : 213.66 = 91.42 : x
  2. Step 2: Convert to fraction form
    142.78/213.66 = 91.42/x
  3. Step 3: Cross multiply
    142.78x = 213.66 × 91.42
  4. Step 4: Simplify right side
    142.78x = 19,532.80
  5. Step 5: Solve for x
    x = 19,532.80/142.78
  6. Step 6: Final answer
    x = 136.80

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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.