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Finding the Fourth Proportional to 1,239.72, 1,857.42 and 778.56

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Solution

The fourth proportional to 1,239.72, 1,857.42 and 778.56 is: 1,166.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.72 : 1,857.42 = 778.56 : x
  2. Step 2: Convert to fraction form
    1,239.72/1,857.42 = 778.56/x
  3. Step 3: Cross multiply
    1,239.72x = 1,857.42 × 778.56
  4. Step 4: Simplify right side
    1,239.72x = 1,446,112.92
  5. Step 5: Solve for x
    x = 1,446,112.92/1,239.72
  6. Step 6: Final answer
    x = 1,166.48

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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.