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Finding the Fourth Proportional to 76.28, 105.21 and 56.61

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Solution

The fourth proportional to 76.28, 105.21 and 56.61 is: 78.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.28 : 105.21 = 56.61 : x
  2. Step 2: Convert to fraction form
    76.28/105.21 = 56.61/x
  3. Step 3: Cross multiply
    76.28x = 105.21 × 56.61
  4. Step 4: Simplify right side
    76.28x = 5,955.94
  5. Step 5: Solve for x
    x = 5,955.94/76.28
  6. Step 6: Final answer
    x = 78.09

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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.