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Finding the Fourth Proportional to 871.70, 1,308.47 and 640.85

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Solution

The fourth proportional to 871.70, 1,308.47 and 640.85 is: 961.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.70 : 1,308.47 = 640.85 : x
  2. Step 2: Convert to fraction form
    871.70/1,308.47 = 640.85/x
  3. Step 3: Cross multiply
    871.70x = 1,308.47 × 640.85
  4. Step 4: Simplify right side
    871.70x = 838,533.07
  5. Step 5: Solve for x
    x = 838,533.07/871.70
  6. Step 6: Final answer
    x = 961.95

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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.