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Finding the Fourth Proportional to 439.12, 661.39 and 428.19

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Solution

The fourth proportional to 439.12, 661.39 and 428.19 is: 644.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    439.12 : 661.39 = 428.19 : x
  2. Step 2: Convert to fraction form
    439.12/661.39 = 428.19/x
  3. Step 3: Cross multiply
    439.12x = 661.39 × 428.19
  4. Step 4: Simplify right side
    439.12x = 283,200.58
  5. Step 5: Solve for x
    x = 283,200.58/439.12
  6. Step 6: Final answer
    x = 644.93

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.