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Finding the Fourth Proportional to 820.99, 1,231.49 and 388.45

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Solution

The fourth proportional to 820.99, 1,231.49 and 388.45 is: 582.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.99 : 1,231.49 = 388.45 : x
  2. Step 2: Convert to fraction form
    820.99/1,231.49 = 388.45/x
  3. Step 3: Cross multiply
    820.99x = 1,231.49 × 388.45
  4. Step 4: Simplify right side
    820.99x = 478,372.29
  5. Step 5: Solve for x
    x = 478,372.29/820.99
  6. Step 6: Final answer
    x = 582.68

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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.