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Finding the Fourth Proportional to 854.78, 1,282.24 and 639.72

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Solution

The fourth proportional to 854.78, 1,282.24 and 639.72 is: 959.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    854.78 : 1,282.24 = 639.72 : x
  2. Step 2: Convert to fraction form
    854.78/1,282.24 = 639.72/x
  3. Step 3: Cross multiply
    854.78x = 1,282.24 × 639.72
  4. Step 4: Simplify right side
    854.78x = 820,274.57
  5. Step 5: Solve for x
    x = 820,274.57/854.78
  6. Step 6: Final answer
    x = 959.63

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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.