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Finding the Fourth Proportional to 780.67, 1,170.17 and 389.90

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Solution

The fourth proportional to 780.67, 1,170.17 and 389.90 is: 584.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.67 : 1,170.17 = 389.90 : x
  2. Step 2: Convert to fraction form
    780.67/1,170.17 = 389.90/x
  3. Step 3: Cross multiply
    780.67x = 1,170.17 × 389.90
  4. Step 4: Simplify right side
    780.67x = 456,250.26
  5. Step 5: Solve for x
    x = 456,250.26/780.67
  6. Step 6: Final answer
    x = 584.44

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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.