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Finding the Fourth Proportional to 645.78, 891.06 and 397.08

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Solution

The fourth proportional to 645.78, 891.06 and 397.08 is: 547.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.78 : 891.06 = 397.08 : x
  2. Step 2: Convert to fraction form
    645.78/891.06 = 397.08/x
  3. Step 3: Cross multiply
    645.78x = 891.06 × 397.08
  4. Step 4: Simplify right side
    645.78x = 353,822.10
  5. Step 5: Solve for x
    x = 353,822.10/645.78
  6. Step 6: Final answer
    x = 547.90

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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.