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Finding the Fourth Proportional to 1,289.94, 1,934.91 and 640.68

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Solution

The fourth proportional to 1,289.94, 1,934.91 and 640.68 is: 961.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.94 : 1,934.91 = 640.68 : x
  2. Step 2: Convert to fraction form
    1,289.94/1,934.91 = 640.68/x
  3. Step 3: Cross multiply
    1,289.94x = 1,934.91 × 640.68
  4. Step 4: Simplify right side
    1,289.94x = 1,239,658.14
  5. Step 5: Solve for x
    x = 1,239,658.14/1,289.94
  6. Step 6: Final answer
    x = 961.02

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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.