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Finding the Fourth Proportional to 1,938.38, 2,907.70 and 639.86

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Solution

The fourth proportional to 1,938.38, 2,907.70 and 639.86 is: 959.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,938.38 : 2,907.70 = 639.86 : x
  2. Step 2: Convert to fraction form
    1,938.38/2,907.70 = 639.86/x
  3. Step 3: Cross multiply
    1,938.38x = 2,907.70 × 639.86
  4. Step 4: Simplify right side
    1,938.38x = 1,860,520.92
  5. Step 5: Solve for x
    x = 1,860,520.92/1,938.38
  6. Step 6: Final answer
    x = 959.83

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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.