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Finding the Fourth Proportional to 98.66, 135.96 and 81.20

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Solution

The fourth proportional to 98.66, 135.96 and 81.20 is: 111.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.66 : 135.96 = 81.20 : x
  2. Step 2: Convert to fraction form
    98.66/135.96 = 81.20/x
  3. Step 3: Cross multiply
    98.66x = 135.96 × 81.20
  4. Step 4: Simplify right side
    98.66x = 11,039.95
  5. Step 5: Solve for x
    x = 11,039.95/98.66
  6. Step 6: Final answer
    x = 111.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.