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Finding the Fourth Proportional to 318.66, 438.05 and 285.09

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Solution

The fourth proportional to 318.66, 438.05 and 285.09 is: 391.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.66 : 438.05 = 285.09 : x
  2. Step 2: Convert to fraction form
    318.66/438.05 = 285.09/x
  3. Step 3: Cross multiply
    318.66x = 438.05 × 285.09
  4. Step 4: Simplify right side
    318.66x = 124,883.67
  5. Step 5: Solve for x
    x = 124,883.67/318.66
  6. Step 6: Final answer
    x = 391.90

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.