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Finding the Fourth Proportional to 78.20, 117.15 and 47.68

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Solution

The fourth proportional to 78.20, 117.15 and 47.68 is: 71.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.20 : 117.15 = 47.68 : x
  2. Step 2: Convert to fraction form
    78.20/117.15 = 47.68/x
  3. Step 3: Cross multiply
    78.20x = 117.15 × 47.68
  4. Step 4: Simplify right side
    78.20x = 5,585.71
  5. Step 5: Solve for x
    x = 5,585.71/78.20
  6. Step 6: Final answer
    x = 71.43

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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.