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Finding the Fourth Proportional to 812.22, 1,217.14 and 639.22

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Solution

The fourth proportional to 812.22, 1,217.14 and 639.22 is: 957.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.22 : 1,217.14 = 639.22 : x
  2. Step 2: Convert to fraction form
    812.22/1,217.14 = 639.22/x
  3. Step 3: Cross multiply
    812.22x = 1,217.14 × 639.22
  4. Step 4: Simplify right side
    812.22x = 778,020.23
  5. Step 5: Solve for x
    x = 778,020.23/812.22
  6. Step 6: Final answer
    x = 957.89

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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.