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Finding the Fourth Proportional to 820.68, 1,231.08 and 388.20

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Solution

The fourth proportional to 820.68, 1,231.08 and 388.20 is: 582.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.68 : 1,231.08 = 388.20 : x
  2. Step 2: Convert to fraction form
    820.68/1,231.08 = 388.20/x
  3. Step 3: Cross multiply
    820.68x = 1,231.08 × 388.20
  4. Step 4: Simplify right side
    820.68x = 477,905.26
  5. Step 5: Solve for x
    x = 477,905.26/820.68
  6. Step 6: Final answer
    x = 582.33

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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.