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Finding the Fourth Proportional to 780.84, 1,171.26 and 390.83

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Solution

The fourth proportional to 780.84, 1,171.26 and 390.83 is: 586.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.84 : 1,171.26 = 390.83 : x
  2. Step 2: Convert to fraction form
    780.84/1,171.26 = 390.83/x
  3. Step 3: Cross multiply
    780.84x = 1,171.26 × 390.83
  4. Step 4: Simplify right side
    780.84x = 457,757.69
  5. Step 5: Solve for x
    x = 457,757.69/780.84
  6. Step 6: Final answer
    x = 586.24

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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.