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Finding the Fourth Proportional to 390.78, 586.34 and 208.13

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Solution

The fourth proportional to 390.78, 586.34 and 208.13 is: 312.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.78 : 586.34 = 208.13 : x
  2. Step 2: Convert to fraction form
    390.78/586.34 = 208.13/x
  3. Step 3: Cross multiply
    390.78x = 586.34 × 208.13
  4. Step 4: Simplify right side
    390.78x = 122,034.94
  5. Step 5: Solve for x
    x = 122,034.94/390.78
  6. Step 6: Final answer
    x = 312.29

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.