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Finding the Fourth Proportional to 39.89, 55.10 and 30.74

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Solution

The fourth proportional to 39.89, 55.10 and 30.74 is: 42.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.89 : 55.10 = 30.74 : x
  2. Step 2: Convert to fraction form
    39.89/55.10 = 30.74/x
  3. Step 3: Cross multiply
    39.89x = 55.10 × 30.74
  4. Step 4: Simplify right side
    39.89x = 1,693.58
  5. Step 5: Solve for x
    x = 1,693.58/39.89
  6. Step 6: Final answer
    x = 42.45

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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.