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Finding the Fourth Proportional to 1,121.69, 1,682.27 and 428.10

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Solution

The fourth proportional to 1,121.69, 1,682.27 and 428.10 is: 642.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.69 : 1,682.27 = 428.10 : x
  2. Step 2: Convert to fraction form
    1,121.69/1,682.27 = 428.10/x
  3. Step 3: Cross multiply
    1,121.69x = 1,682.27 × 428.10
  4. Step 4: Simplify right side
    1,121.69x = 720,177.65
  5. Step 5: Solve for x
    x = 720,177.65/1,121.69
  6. Step 6: Final answer
    x = 642.05

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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.