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Finding the Fourth Proportional to 78.91, 118.40 and 30.85

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Solution

The fourth proportional to 78.91, 118.40 and 30.85 is: 46.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.91 : 118.40 = 30.85 : x
  2. Step 2: Convert to fraction form
    78.91/118.40 = 30.85/x
  3. Step 3: Cross multiply
    78.91x = 118.40 × 30.85
  4. Step 4: Simplify right side
    78.91x = 3,652.49
  5. Step 5: Solve for x
    x = 3,652.49/78.91
  6. Step 6: Final answer
    x = 46.29

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.