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Finding the Fourth Proportional to 1,291, 1,781.70 and 739

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Solution

The fourth proportional to 1,291, 1,781.70 and 739 is: 1,019.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291 : 1,781.70 = 739 : x
  2. Step 2: Convert to fraction form
    1,291/1,781.70 = 739/x
  3. Step 3: Cross multiply
    1,291x = 1,781.70 × 739
  4. Step 4: Simplify right side
    1,291x = 1,316,676.30
  5. Step 5: Solve for x
    x = 1,316,676.30/1,291
  6. Step 6: Final answer
    x = 1,019.89

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.