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Finding the Fourth Proportional to 39.05, 53.89 and 21.57

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Solution

The fourth proportional to 39.05, 53.89 and 21.57 is: 29.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.05 : 53.89 = 21.57 : x
  2. Step 2: Convert to fraction form
    39.05/53.89 = 21.57/x
  3. Step 3: Cross multiply
    39.05x = 53.89 × 21.57
  4. Step 4: Simplify right side
    39.05x = 1,162.39
  5. Step 5: Solve for x
    x = 1,162.39/39.05
  6. Step 6: Final answer
    x = 29.76

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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.