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Finding the Fourth Proportional to 39.12, 53.90 and 30.92

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Solution

The fourth proportional to 39.12, 53.90 and 30.92 is: 42.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.12 : 53.90 = 30.92 : x
  2. Step 2: Convert to fraction form
    39.12/53.90 = 30.92/x
  3. Step 3: Cross multiply
    39.12x = 53.90 × 30.92
  4. Step 4: Simplify right side
    39.12x = 1,666.59
  5. Step 5: Solve for x
    x = 1,666.59/39.12
  6. Step 6: Final answer
    x = 42.60

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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.