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Finding the Fourth Proportional to 820.23, 1,228.05 and 639.74

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Solution

The fourth proportional to 820.23, 1,228.05 and 639.74 is: 957.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.23 : 1,228.05 = 639.74 : x
  2. Step 2: Convert to fraction form
    820.23/1,228.05 = 639.74/x
  3. Step 3: Cross multiply
    820.23x = 1,228.05 × 639.74
  4. Step 4: Simplify right side
    820.23x = 785,632.71
  5. Step 5: Solve for x
    x = 785,632.71/820.23
  6. Step 6: Final answer
    x = 957.82

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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.