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Finding the Fourth Proportional to 390.84, 539.36 and 213.80

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Solution

The fourth proportional to 390.84, 539.36 and 213.80 is: 295.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.84 : 539.36 = 213.80 : x
  2. Step 2: Convert to fraction form
    390.84/539.36 = 213.80/x
  3. Step 3: Cross multiply
    390.84x = 539.36 × 213.80
  4. Step 4: Simplify right side
    390.84x = 115,315.98
  5. Step 5: Solve for x
    x = 115,315.98/390.84
  6. Step 6: Final answer
    x = 295.05

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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.