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Finding the Fourth Proportional to 1,121.69, 1,682.19 and 427.85

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Solution

The fourth proportional to 1,121.69, 1,682.19 and 427.85 is: 641.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.69 : 1,682.19 = 427.85 : x
  2. Step 2: Convert to fraction form
    1,121.69/1,682.19 = 427.85/x
  3. Step 3: Cross multiply
    1,121.69x = 1,682.19 × 427.85
  4. Step 4: Simplify right side
    1,121.69x = 719,716.58
  5. Step 5: Solve for x
    x = 719,716.58/1,121.69
  6. Step 6: Final answer
    x = 641.64

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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.