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Finding the Fourth Proportional to 30,969.62, 42,755.80 and 20,390

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Solution

The fourth proportional to 30,969.62, 42,755.80 and 20,390 is: 28,149.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    30,969.62 : 42,755.80 = 20,390 : x
  2. Step 2: Convert to fraction form
    30,969.62/42,755.80 = 20,390/x
  3. Step 3: Cross multiply
    30,969.62x = 42,755.80 × 20,390
  4. Step 4: Simplify right side
    30,969.62x = 871,790,762
  5. Step 5: Solve for x
    x = 871,790,762/30,969.62
  6. Step 6: Final answer
    x = 28,149.87

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.