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Finding the Fourth Proportional to 56.78, 78.36 and 30.91

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Solution

The fourth proportional to 56.78, 78.36 and 30.91 is: 42.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    56.78 : 78.36 = 30.91 : x
  2. Step 2: Convert to fraction form
    56.78/78.36 = 30.91/x
  3. Step 3: Cross multiply
    56.78x = 78.36 × 30.91
  4. Step 4: Simplify right side
    56.78x = 2,421.78
  5. Step 5: Solve for x
    x = 2,421.78/56.78
  6. Step 6: Final answer
    x = 42.65

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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.