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Finding the Fourth Proportional to 39.15, 54.02 and 21.66

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Solution

The fourth proportional to 39.15, 54.02 and 21.66 is: 29.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.15 : 54.02 = 21.66 : x
  2. Step 2: Convert to fraction form
    39.15/54.02 = 21.66/x
  3. Step 3: Cross multiply
    39.15x = 54.02 × 21.66
  4. Step 4: Simplify right side
    39.15x = 1,170.07
  5. Step 5: Solve for x
    x = 1,170.07/39.15
  6. Step 6: Final answer
    x = 29.89

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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.