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Finding the Fourth Proportional to 1,120.36, 1,680.30 and 427

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Solution

The fourth proportional to 1,120.36, 1,680.30 and 427 is: 640.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,120.36 : 1,680.30 = 427 : x
  2. Step 2: Convert to fraction form
    1,120.36/1,680.30 = 427/x
  3. Step 3: Cross multiply
    1,120.36x = 1,680.30 × 427
  4. Step 4: Simplify right side
    1,120.36x = 717,488.10
  5. Step 5: Solve for x
    x = 717,488.10/1,120.36
  6. Step 6: Final answer
    x = 640.41

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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.