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Finding the Fourth Proportional to 661.38, 990.99 and 387.42

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Solution

The fourth proportional to 661.38, 990.99 and 387.42 is: 580.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.38 : 990.99 = 387.42 : x
  2. Step 2: Convert to fraction form
    661.38/990.99 = 387.42/x
  3. Step 3: Cross multiply
    661.38x = 990.99 × 387.42
  4. Step 4: Simplify right side
    661.38x = 383,929.35
  5. Step 5: Solve for x
    x = 383,929.35/661.38
  6. Step 6: Final answer
    x = 580.50

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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.