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Finding the Fourth Proportional to 774.78, 1,069.19 and 420.71

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Solution

The fourth proportional to 774.78, 1,069.19 and 420.71 is: 580.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    774.78 : 1,069.19 = 420.71 : x
  2. Step 2: Convert to fraction form
    774.78/1,069.19 = 420.71/x
  3. Step 3: Cross multiply
    774.78x = 1,069.19 × 420.71
  4. Step 4: Simplify right side
    774.78x = 449,813.05
  5. Step 5: Solve for x
    x = 449,813.05/774.78
  6. Step 6: Final answer
    x = 580.57

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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.