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Finding the Fourth Proportional to 318.68, 439.89 and 309.90

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Solution

The fourth proportional to 318.68, 439.89 and 309.90 is: 427.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.68 : 439.89 = 309.90 : x
  2. Step 2: Convert to fraction form
    318.68/439.89 = 309.90/x
  3. Step 3: Cross multiply
    318.68x = 439.89 × 309.90
  4. Step 4: Simplify right side
    318.68x = 136,322.54
  5. Step 5: Solve for x
    x = 136,322.54/318.68
  6. Step 6: Final answer
    x = 427.78

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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.