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Finding the Fourth Proportional to 39.70, 54.81 and 30.47

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Solution

The fourth proportional to 39.70, 54.81 and 30.47 is: 42.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.70 : 54.81 = 30.47 : x
  2. Step 2: Convert to fraction form
    39.70/54.81 = 30.47/x
  3. Step 3: Cross multiply
    39.70x = 54.81 × 30.47
  4. Step 4: Simplify right side
    39.70x = 1,670.02
  5. Step 5: Solve for x
    x = 1,670.02/39.70
  6. Step 6: Final answer
    x = 42.07

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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.