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Finding the Fourth Proportional to 645.81, 891.06 and 393.87

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Solution

The fourth proportional to 645.81, 891.06 and 393.87 is: 543.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.81 : 891.06 = 393.87 : x
  2. Step 2: Convert to fraction form
    645.81/891.06 = 393.87/x
  3. Step 3: Cross multiply
    645.81x = 891.06 × 393.87
  4. Step 4: Simplify right side
    645.81x = 350,961.80
  5. Step 5: Solve for x
    x = 350,961.80/645.81
  6. Step 6: Final answer
    x = 543.44

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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.