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Finding the Fourth Proportional to 98.40, 135.36 and 81.12

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Solution

The fourth proportional to 98.40, 135.36 and 81.12 is: 111.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.40 : 135.36 = 81.12 : x
  2. Step 2: Convert to fraction form
    98.40/135.36 = 81.12/x
  3. Step 3: Cross multiply
    98.40x = 135.36 × 81.12
  4. Step 4: Simplify right side
    98.40x = 10,980.40
  5. Step 5: Solve for x
    x = 10,980.40/98.40
  6. Step 6: Final answer
    x = 111.59

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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.