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Finding the Fourth Proportional to 81.57, 112.38 and 56.65

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Solution

The fourth proportional to 81.57, 112.38 and 56.65 is: 78.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.57 : 112.38 = 56.65 : x
  2. Step 2: Convert to fraction form
    81.57/112.38 = 56.65/x
  3. Step 3: Cross multiply
    81.57x = 112.38 × 56.65
  4. Step 4: Simplify right side
    81.57x = 6,366.33
  5. Step 5: Solve for x
    x = 6,366.33/81.57
  6. Step 6: Final answer
    x = 78.05

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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.