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Finding the Fourth Proportional to 78.70, 108.58 and 54.15

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Solution

The fourth proportional to 78.70, 108.58 and 54.15 is: 74.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.70 : 108.58 = 54.15 : x
  2. Step 2: Convert to fraction form
    78.70/108.58 = 54.15/x
  3. Step 3: Cross multiply
    78.70x = 108.58 × 54.15
  4. Step 4: Simplify right side
    78.70x = 5,879.61
  5. Step 5: Solve for x
    x = 5,879.61/78.70
  6. Step 6: Final answer
    x = 74.71

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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.