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Finding the Fourth Proportional to 98.69, 135.81 and 77.90

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Solution

The fourth proportional to 98.69, 135.81 and 77.90 is: 107.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.69 : 135.81 = 77.90 : x
  2. Step 2: Convert to fraction form
    98.69/135.81 = 77.90/x
  3. Step 3: Cross multiply
    98.69x = 135.81 × 77.90
  4. Step 4: Simplify right side
    98.69x = 10,578.92
  5. Step 5: Solve for x
    x = 10,578.92/98.69
  6. Step 6: Final answer
    x = 107.20

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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.