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Finding the Fourth Proportional to 309.05, 426.90 and 287.18

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Solution

The fourth proportional to 309.05, 426.90 and 287.18 is: 396.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.05 : 426.90 = 287.18 : x
  2. Step 2: Convert to fraction form
    309.05/426.90 = 287.18/x
  3. Step 3: Cross multiply
    309.05x = 426.90 × 287.18
  4. Step 4: Simplify right side
    309.05x = 122,597.14
  5. Step 5: Solve for x
    x = 122,597.14/309.05
  6. Step 6: Final answer
    x = 396.69

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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.