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Finding the Fourth Proportional to 1,215.23, 1,819.80 and 905.40

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Solution

The fourth proportional to 1,215.23, 1,819.80 and 905.40 is: 1,355.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,215.23 : 1,819.80 = 905.40 : x
  2. Step 2: Convert to fraction form
    1,215.23/1,819.80 = 905.40/x
  3. Step 3: Cross multiply
    1,215.23x = 1,819.80 × 905.40
  4. Step 4: Simplify right side
    1,215.23x = 1,647,646.92
  5. Step 5: Solve for x
    x = 1,647,646.92/1,215.23
  6. Step 6: Final answer
    x = 1,355.83

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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.