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Finding the Fourth Proportional to 158.78, 238.15 and 81.70

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Solution

The fourth proportional to 158.78, 238.15 and 81.70 is: 122.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    158.78 : 238.15 = 81.70 : x
  2. Step 2: Convert to fraction form
    158.78/238.15 = 81.70/x
  3. Step 3: Cross multiply
    158.78x = 238.15 × 81.70
  4. Step 4: Simplify right side
    158.78x = 19,456.06
  5. Step 5: Solve for x
    x = 19,456.06/158.78
  6. Step 6: Final answer
    x = 122.54

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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.