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Finding the Fourth Proportional to 78.20, 117.16 and 47.76

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Solution

The fourth proportional to 78.20, 117.16 and 47.76 is: 71.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.20 : 117.16 = 47.76 : x
  2. Step 2: Convert to fraction form
    78.20/117.16 = 47.76/x
  3. Step 3: Cross multiply
    78.20x = 117.16 × 47.76
  4. Step 4: Simplify right side
    78.20x = 5,595.56
  5. Step 5: Solve for x
    x = 5,595.56/78.20
  6. Step 6: Final answer
    x = 71.55

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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.