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Finding the Fourth Proportional to 390.90, 539.28 and 243.72

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Solution

The fourth proportional to 390.90, 539.28 and 243.72 is: 336.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.90 : 539.28 = 243.72 : x
  2. Step 2: Convert to fraction form
    390.90/539.28 = 243.72/x
  3. Step 3: Cross multiply
    390.90x = 539.28 × 243.72
  4. Step 4: Simplify right side
    390.90x = 131,433.32
  5. Step 5: Solve for x
    x = 131,433.32/390.90
  6. Step 6: Final answer
    x = 336.23

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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.