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Finding the Fourth Proportional to 81.25, 112 and 56.65

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Solution

The fourth proportional to 81.25, 112 and 56.65 is: 78.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.25 : 112 = 56.65 : x
  2. Step 2: Convert to fraction form
    81.25/112 = 56.65/x
  3. Step 3: Cross multiply
    81.25x = 112 × 56.65
  4. Step 4: Simplify right side
    81.25x = 6,344.80
  5. Step 5: Solve for x
    x = 6,344.80/81.25
  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.