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Finding the Fourth Proportional to 39.12, 53.99 and 21.64

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Solution

The fourth proportional to 39.12, 53.99 and 21.64 is: 29.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.12 : 53.99 = 21.64 : x
  2. Step 2: Convert to fraction form
    39.12/53.99 = 21.64/x
  3. Step 3: Cross multiply
    39.12x = 53.99 × 21.64
  4. Step 4: Simplify right side
    39.12x = 1,167.97
  5. Step 5: Solve for x
    x = 1,167.97/39.12
  6. Step 6: Final answer
    x = 29.86

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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.