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Finding the Fourth Proportional to 77.87, 107.36 and 72.40

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Solution

The fourth proportional to 77.87, 107.36 and 72.40 is: 99.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.87 : 107.36 = 72.40 : x
  2. Step 2: Convert to fraction form
    77.87/107.36 = 72.40/x
  3. Step 3: Cross multiply
    77.87x = 107.36 × 72.40
  4. Step 4: Simplify right side
    77.87x = 7,772.78
  5. Step 5: Solve for x
    x = 7,772.78/77.87
  6. Step 6: Final answer
    x = 99.82

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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.