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Finding the Fourth Proportional to 1,291.05, 1,780.43 and 939.29

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Solution

The fourth proportional to 1,291.05, 1,780.43 and 939.29 is: 1,295.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,291.05 : 1,780.43 = 939.29 : x
  2. Step 2: Convert to fraction form
    1,291.05/1,780.43 = 939.29/x
  3. Step 3: Cross multiply
    1,291.05x = 1,780.43 × 939.29
  4. Step 4: Simplify right side
    1,291.05x = 1,672,326.50
  5. Step 5: Solve for x
    x = 1,672,326.50/1,291.05
  6. Step 6: Final answer
    x = 1,295.32

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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.