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Finding the Fourth Proportional to 1,639.47, 2,455.92 and 815.21

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Solution

The fourth proportional to 1,639.47, 2,455.92 and 815.21 is: 1,221.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,639.47 : 2,455.92 = 815.21 : x
  2. Step 2: Convert to fraction form
    1,639.47/2,455.92 = 815.21/x
  3. Step 3: Cross multiply
    1,639.47x = 2,455.92 × 815.21
  4. Step 4: Simplify right side
    1,639.47x = 2,002,078.26
  5. Step 5: Solve for x
    x = 2,002,078.26/1,639.47
  6. Step 6: Final answer
    x = 1,221.17

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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.