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Finding the Fourth Proportional to 78.91, 108.89 and 47.80

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Solution

The fourth proportional to 78.91, 108.89 and 47.80 is: 65.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.91 : 108.89 = 47.80 : x
  2. Step 2: Convert to fraction form
    78.91/108.89 = 47.80/x
  3. Step 3: Cross multiply
    78.91x = 108.89 × 47.80
  4. Step 4: Simplify right side
    78.91x = 5,204.94
  5. Step 5: Solve for x
    x = 5,204.94/78.91
  6. Step 6: Final answer
    x = 65.96

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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.