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Finding the Fourth Proportional to 645, 890.28 and 438

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Solution

The fourth proportional to 645, 890.28 and 438 is: 604.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    645 : 890.28 = 438 : x
  2. Step 2: Convert to fraction form
    645/890.28 = 438/x
  3. Step 3: Cross multiply
    645x = 890.28 × 438
  4. Step 4: Simplify right side
    645x = 389,942.64
  5. Step 5: Solve for x
    x = 389,942.64/645
  6. Step 6: Final answer
    x = 604.56

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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.