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Finding the Fourth Proportional to 811.62, 1,216.04 and 639.39

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Solution

The fourth proportional to 811.62, 1,216.04 and 639.39 is: 957.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.62 : 1,216.04 = 639.39 : x
  2. Step 2: Convert to fraction form
    811.62/1,216.04 = 639.39/x
  3. Step 3: Cross multiply
    811.62x = 1,216.04 × 639.39
  4. Step 4: Simplify right side
    811.62x = 777,520.62
  5. Step 5: Solve for x
    x = 777,520.62/811.62
  6. Step 6: Final answer
    x = 957.99

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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.