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Finding the Fourth Proportional to 1,270.75, 1,905.43 and 686.45

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Solution

The fourth proportional to 1,270.75, 1,905.43 and 686.45 is: 1,029.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,270.75 : 1,905.43 = 686.45 : x
  2. Step 2: Convert to fraction form
    1,270.75/1,905.43 = 686.45/x
  3. Step 3: Cross multiply
    1,270.75x = 1,905.43 × 686.45
  4. Step 4: Simplify right side
    1,270.75x = 1,307,982.42
  5. Step 5: Solve for x
    x = 1,307,982.42/1,270.75
  6. Step 6: Final answer
    x = 1,029.30

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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.