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Finding the Fourth Proportional to 3,938, 5,909.28 and 1,990.40

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Solution

The fourth proportional to 3,938, 5,909.28 and 1,990.40 is: 2,986.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,938 : 5,909.28 = 1,990.40 : x
  2. Step 2: Convert to fraction form
    3,938/5,909.28 = 1,990.40/x
  3. Step 3: Cross multiply
    3,938x = 5,909.28 × 1,990.40
  4. Step 4: Simplify right side
    3,938x = 11,761,830.91
  5. Step 5: Solve for x
    x = 11,761,830.91/3,938
  6. Step 6: Final answer
    x = 2,986.75

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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.