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Finding the Fourth Proportional to 77.65, 115.90 and 72.30

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Solution

The fourth proportional to 77.65, 115.90 and 72.30 is: 107.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.65 : 115.90 = 72.30 : x
  2. Step 2: Convert to fraction form
    77.65/115.90 = 72.30/x
  3. Step 3: Cross multiply
    77.65x = 115.90 × 72.30
  4. Step 4: Simplify right side
    77.65x = 8,379.57
  5. Step 5: Solve for x
    x = 8,379.57/77.65
  6. Step 6: Final answer
    x = 107.91

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.