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Finding the Fourth Proportional to 80.78, 111.44 and 56.21

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Solution

The fourth proportional to 80.78, 111.44 and 56.21 is: 77.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.78 : 111.44 = 56.21 : x
  2. Step 2: Convert to fraction form
    80.78/111.44 = 56.21/x
  3. Step 3: Cross multiply
    80.78x = 111.44 × 56.21
  4. Step 4: Simplify right side
    80.78x = 6,263.63
  5. Step 5: Solve for x
    x = 6,263.63/80.78
  6. Step 6: Final answer
    x = 77.54

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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.