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Finding the Fourth Proportional to 1,399.89, 1,931.85 and 778.89

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Solution

The fourth proportional to 1,399.89, 1,931.85 and 778.89 is: 1,074.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,399.89 : 1,931.85 = 778.89 : x
  2. Step 2: Convert to fraction form
    1,399.89/1,931.85 = 778.89/x
  3. Step 3: Cross multiply
    1,399.89x = 1,931.85 × 778.89
  4. Step 4: Simplify right side
    1,399.89x = 1,504,698.65
  5. Step 5: Solve for x
    x = 1,504,698.65/1,399.89
  6. Step 6: Final answer
    x = 1,074.87

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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.