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Finding the Fourth Proportional to 318.11, 439.04 and 309.78

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Solution

The fourth proportional to 318.11, 439.04 and 309.78 is: 427.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.11 : 439.04 = 309.78 : x
  2. Step 2: Convert to fraction form
    318.11/439.04 = 309.78/x
  3. Step 3: Cross multiply
    318.11x = 439.04 × 309.78
  4. Step 4: Simplify right side
    318.11x = 136,004.26
  5. Step 5: Solve for x
    x = 136,004.26/318.11
  6. Step 6: Final answer
    x = 427.55

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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.