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Finding the Fourth Proportional to 1,938.21, 2,906.91 and 639.38

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Solution

The fourth proportional to 1,938.21, 2,906.91 and 639.38 is: 958.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,938.21 : 2,906.91 = 639.38 : x
  2. Step 2: Convert to fraction form
    1,938.21/2,906.91 = 639.38/x
  3. Step 3: Cross multiply
    1,938.21x = 2,906.91 × 639.38
  4. Step 4: Simplify right side
    1,938.21x = 1,858,620.12
  5. Step 5: Solve for x
    x = 1,858,620.12/1,938.21
  6. Step 6: Final answer
    x = 958.94

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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.