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Finding the Fourth Proportional to 285.31, 428.09 and 138.98

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Solution

The fourth proportional to 285.31, 428.09 and 138.98 is: 208.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.31 : 428.09 = 138.98 : x
  2. Step 2: Convert to fraction form
    285.31/428.09 = 138.98/x
  3. Step 3: Cross multiply
    285.31x = 428.09 × 138.98
  4. Step 4: Simplify right side
    285.31x = 59,495.95
  5. Step 5: Solve for x
    x = 59,495.95/285.31
  6. Step 6: Final answer
    x = 208.53

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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.