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Finding the Fourth Proportional to 74.20, 102.42 and 55.78

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Solution

The fourth proportional to 74.20, 102.42 and 55.78 is: 76.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.20 : 102.42 = 55.78 : x
  2. Step 2: Convert to fraction form
    74.20/102.42 = 55.78/x
  3. Step 3: Cross multiply
    74.20x = 102.42 × 55.78
  4. Step 4: Simplify right side
    74.20x = 5,712.99
  5. Step 5: Solve for x
    x = 5,712.99/74.20
  6. Step 6: Final answer
    x = 76.99

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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.