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Finding the Fourth Proportional to 309.90, 428.10 and 216.90

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Solution

The fourth proportional to 309.90, 428.10 and 216.90 is: 299.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.90 : 428.10 = 216.90 : x
  2. Step 2: Convert to fraction form
    309.90/428.10 = 216.90/x
  3. Step 3: Cross multiply
    309.90x = 428.10 × 216.90
  4. Step 4: Simplify right side
    309.90x = 92,854.89
  5. Step 5: Solve for x
    x = 92,854.89/309.90
  6. Step 6: Final answer
    x = 299.63

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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.