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Finding the Fourth Proportional to 98.40, 135.96 and 77.76

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Solution

The fourth proportional to 98.40, 135.96 and 77.76 is: 107.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.40 : 135.96 = 77.76 : x
  2. Step 2: Convert to fraction form
    98.40/135.96 = 77.76/x
  3. Step 3: Cross multiply
    98.40x = 135.96 × 77.76
  4. Step 4: Simplify right side
    98.40x = 10,572.25
  5. Step 5: Solve for x
    x = 10,572.25/98.40
  6. Step 6: Final answer
    x = 107.44

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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.