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Finding the Fourth Proportional to 1,271.55, 1,905.73 and 685.09

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Solution

The fourth proportional to 1,271.55, 1,905.73 and 685.09 is: 1,026.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,271.55 : 1,905.73 = 685.09 : x
  2. Step 2: Convert to fraction form
    1,271.55/1,905.73 = 685.09/x
  3. Step 3: Cross multiply
    1,271.55x = 1,905.73 × 685.09
  4. Step 4: Simplify right side
    1,271.55x = 1,305,596.57
  5. Step 5: Solve for x
    x = 1,305,596.57/1,271.55
  6. Step 6: Final answer
    x = 1,026.78

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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.