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Finding the Fourth Proportional to 390.98, 539.34 and 280.22

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Solution

The fourth proportional to 390.98, 539.34 and 280.22 is: 386.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.98 : 539.34 = 280.22 : x
  2. Step 2: Convert to fraction form
    390.98/539.34 = 280.22/x
  3. Step 3: Cross multiply
    390.98x = 539.34 × 280.22
  4. Step 4: Simplify right side
    390.98x = 151,133.85
  5. Step 5: Solve for x
    x = 151,133.85/390.98
  6. Step 6: Final answer
    x = 386.55

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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.