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Finding the Fourth Proportional to 79.38, 109.49 and 51.78

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Solution

The fourth proportional to 79.38, 109.49 and 51.78 is: 71.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.38 : 109.49 = 51.78 : x
  2. Step 2: Convert to fraction form
    79.38/109.49 = 51.78/x
  3. Step 3: Cross multiply
    79.38x = 109.49 × 51.78
  4. Step 4: Simplify right side
    79.38x = 5,669.13
  5. Step 5: Solve for x
    x = 5,669.13/79.38
  6. Step 6: Final answer
    x = 71.42

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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.