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Finding the Fourth Proportional to 780.21, 1,169.97 and 389.91

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Solution

The fourth proportional to 780.21, 1,169.97 and 389.91 is: 584.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.21 : 1,169.97 = 389.91 : x
  2. Step 2: Convert to fraction form
    780.21/1,169.97 = 389.91/x
  3. Step 3: Cross multiply
    780.21x = 1,169.97 × 389.91
  4. Step 4: Simplify right side
    780.21x = 456,183.00
  5. Step 5: Solve for x
    x = 456,183.00/780.21
  6. Step 6: Final answer
    x = 584.69

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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.