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Finding the Fourth Proportional to 390.72, 539.16 and 243.40

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Solution

The fourth proportional to 390.72, 539.16 and 243.40 is: 335.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.72 : 539.16 = 243.40 : x
  2. Step 2: Convert to fraction form
    390.72/539.16 = 243.40/x
  3. Step 3: Cross multiply
    390.72x = 539.16 × 243.40
  4. Step 4: Simplify right side
    390.72x = 131,231.54
  5. Step 5: Solve for x
    x = 131,231.54/390.72
  6. Step 6: Final answer
    x = 335.87

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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.