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Finding the Fourth Proportional to 77.46, 115.40 and 72.80

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Solution

The fourth proportional to 77.46, 115.40 and 72.80 is: 108.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.46 : 115.40 = 72.80 : x
  2. Step 2: Convert to fraction form
    77.46/115.40 = 72.80/x
  3. Step 3: Cross multiply
    77.46x = 115.40 × 72.80
  4. Step 4: Simplify right side
    77.46x = 8,400.18
  5. Step 5: Solve for x
    x = 8,400.18/77.46
  6. Step 6: Final answer
    x = 108.45

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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.