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Finding the Fourth Proportional to 678.72, 1,023.10 and 639.08

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Solution

The fourth proportional to 678.72, 1,023.10 and 639.08 is: 963.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.72 : 1,023.10 = 639.08 : x
  2. Step 2: Convert to fraction form
    678.72/1,023.10 = 639.08/x
  3. Step 3: Cross multiply
    678.72x = 1,023.10 × 639.08
  4. Step 4: Simplify right side
    678.72x = 653,839.55
  5. Step 5: Solve for x
    x = 653,839.55/678.72
  6. Step 6: Final answer
    x = 963.34

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.