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Finding the Fourth Proportional to 678.20, 1,017.12 and 261.64

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Solution

The fourth proportional to 678.20, 1,017.12 and 261.64 is: 392.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.20 : 1,017.12 = 261.64 : x
  2. Step 2: Convert to fraction form
    678.20/1,017.12 = 261.64/x
  3. Step 3: Cross multiply
    678.20x = 1,017.12 × 261.64
  4. Step 4: Simplify right side
    678.20x = 266,119.28
  5. Step 5: Solve for x
    x = 266,119.28/678.20
  6. Step 6: Final answer
    x = 392.39

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.