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Finding the Fourth Proportional to 821.05, 1,231.21 and 307.69

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Solution

The fourth proportional to 821.05, 1,231.21 and 307.69 is: 461.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.05 : 1,231.21 = 307.69 : x
  2. Step 2: Convert to fraction form
    821.05/1,231.21 = 307.69/x
  3. Step 3: Cross multiply
    821.05x = 1,231.21 × 307.69
  4. Step 4: Simplify right side
    821.05x = 378,831.00
  5. Step 5: Solve for x
    x = 378,831.00/821.05
  6. Step 6: Final answer
    x = 461.40

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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.