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Finding the Fourth Proportional to 1,938.20, 2,907.42 and 639.68

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Solution

The fourth proportional to 1,938.20, 2,907.42 and 639.68 is: 959.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,938.20 : 2,907.42 = 639.68 : x
  2. Step 2: Convert to fraction form
    1,938.20/2,907.42 = 639.68/x
  3. Step 3: Cross multiply
    1,938.20x = 2,907.42 × 639.68
  4. Step 4: Simplify right side
    1,938.20x = 1,859,818.43
  5. Step 5: Solve for x
    x = 1,859,818.43/1,938.20
  6. Step 6: Final answer
    x = 959.56

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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.