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Finding the Fourth Proportional to 639.40, 959.40 and 486.28

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Solution

The fourth proportional to 639.40, 959.40 and 486.28 is: 729.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.40 : 959.40 = 486.28 : x
  2. Step 2: Convert to fraction form
    639.40/959.40 = 486.28/x
  3. Step 3: Cross multiply
    639.40x = 959.40 × 486.28
  4. Step 4: Simplify right side
    639.40x = 466,537.03
  5. Step 5: Solve for x
    x = 466,537.03/639.40
  6. Step 6: Final answer
    x = 729.65

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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.