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Finding the Fourth Proportional to 78.76, 108.70 and 47.70

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Solution

The fourth proportional to 78.76, 108.70 and 47.70 is: 65.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.76 : 108.70 = 47.70 : x
  2. Step 2: Convert to fraction form
    78.76/108.70 = 47.70/x
  3. Step 3: Cross multiply
    78.76x = 108.70 × 47.70
  4. Step 4: Simplify right side
    78.76x = 5,184.45
  5. Step 5: Solve for x
    x = 5,184.45/78.76
  6. Step 6: Final answer
    x = 65.83

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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.