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Finding the Fourth Proportional to 8,921.60, 13,372.80 and 3,990.40

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Solution

The fourth proportional to 8,921.60, 13,372.80 and 3,990.40 is: 5,981.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    8,921.60 : 13,372.80 = 3,990.40 : x
  2. Step 2: Convert to fraction form
    8,921.60/13,372.80 = 3,990.40/x
  3. Step 3: Cross multiply
    8,921.60x = 13,372.80 × 3,990.40
  4. Step 4: Simplify right side
    8,921.60x = 53,362,821.12
  5. Step 5: Solve for x
    x = 53,362,821.12/8,921.60
  6. Step 6: Final answer
    x = 5,981.31

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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.