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Finding the Fourth Proportional to 645.64, 890.78 and 396.84

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Solution

The fourth proportional to 645.64, 890.78 and 396.84 is: 547.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.64 : 890.78 = 396.84 : x
  2. Step 2: Convert to fraction form
    645.64/890.78 = 396.84/x
  3. Step 3: Cross multiply
    645.64x = 890.78 × 396.84
  4. Step 4: Simplify right side
    645.64x = 353,497.14
  5. Step 5: Solve for x
    x = 353,497.14/645.64
  6. Step 6: Final answer
    x = 547.51

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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.