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Finding the Fourth Proportional to 74.88, 103.20 and 61.92

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Solution

The fourth proportional to 74.88, 103.20 and 61.92 is: 85.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.88 : 103.20 = 61.92 : x
  2. Step 2: Convert to fraction form
    74.88/103.20 = 61.92/x
  3. Step 3: Cross multiply
    74.88x = 103.20 × 61.92
  4. Step 4: Simplify right side
    74.88x = 6,390.14
  5. Step 5: Solve for x
    x = 6,390.14/74.88
  6. Step 6: Final answer
    x = 85.34

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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.