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Finding the Fourth Proportional to 390.80, 539.40 and 280.52

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Solution

The fourth proportional to 390.80, 539.40 and 280.52 is: 387.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.80 : 539.40 = 280.52 : x
  2. Step 2: Convert to fraction form
    390.80/539.40 = 280.52/x
  3. Step 3: Cross multiply
    390.80x = 539.40 × 280.52
  4. Step 4: Simplify right side
    390.80x = 151,312.49
  5. Step 5: Solve for x
    x = 151,312.49/390.80
  6. Step 6: Final answer
    x = 387.19

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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.