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Finding the Fourth Proportional to 75.78, 104.64 and 51.21

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Solution

The fourth proportional to 75.78, 104.64 and 51.21 is: 70.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    75.78 : 104.64 = 51.21 : x
  2. Step 2: Convert to fraction form
    75.78/104.64 = 51.21/x
  3. Step 3: Cross multiply
    75.78x = 104.64 × 51.21
  4. Step 4: Simplify right side
    75.78x = 5,358.61
  5. Step 5: Solve for x
    x = 5,358.61/75.78
  6. Step 6: Final answer
    x = 70.71

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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.