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Finding the Fourth Proportional to 98.78, 148.18 and 80.90

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Solution

The fourth proportional to 98.78, 148.18 and 80.90 is: 121.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.78 : 148.18 = 80.90 : x
  2. Step 2: Convert to fraction form
    98.78/148.18 = 80.90/x
  3. Step 3: Cross multiply
    98.78x = 148.18 × 80.90
  4. Step 4: Simplify right side
    98.78x = 11,987.76
  5. Step 5: Solve for x
    x = 11,987.76/98.78
  6. Step 6: Final answer
    x = 121.36

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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.