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Finding the Fourth Proportional to 872.78, 1,309.23 and 385.74

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Solution

The fourth proportional to 872.78, 1,309.23 and 385.74 is: 578.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    872.78 : 1,309.23 = 385.74 : x
  2. Step 2: Convert to fraction form
    872.78/1,309.23 = 385.74/x
  3. Step 3: Cross multiply
    872.78x = 1,309.23 × 385.74
  4. Step 4: Simplify right side
    872.78x = 505,022.38
  5. Step 5: Solve for x
    x = 505,022.38/872.78
  6. Step 6: Final answer
    x = 578.64

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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.