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Finding the Fourth Proportional to 39.40, 54.38 and 21.92

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Solution

The fourth proportional to 39.40, 54.38 and 21.92 is: 30.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.40 : 54.38 = 21.92 : x
  2. Step 2: Convert to fraction form
    39.40/54.38 = 21.92/x
  3. Step 3: Cross multiply
    39.40x = 54.38 × 21.92
  4. Step 4: Simplify right side
    39.40x = 1,191.84
  5. Step 5: Solve for x
    x = 1,191.84/39.40
  6. Step 6: Final answer
    x = 30.25

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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.