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Finding the Fourth Proportional to 78.05, 107.78 and 61.71

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Solution

The fourth proportional to 78.05, 107.78 and 61.71 is: 85.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.05 : 107.78 = 61.71 : x
  2. Step 2: Convert to fraction form
    78.05/107.78 = 61.71/x
  3. Step 3: Cross multiply
    78.05x = 107.78 × 61.71
  4. Step 4: Simplify right side
    78.05x = 6,650.80
  5. Step 5: Solve for x
    x = 6,650.80/78.05
  6. Step 6: Final answer
    x = 85.22

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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.