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Finding the Fourth Proportional to 660.68, 991.19 and 387

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Solution

The fourth proportional to 660.68, 991.19 and 387 is: 580.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.68 : 991.19 = 387 : x
  2. Step 2: Convert to fraction form
    660.68/991.19 = 387/x
  3. Step 3: Cross multiply
    660.68x = 991.19 × 387
  4. Step 4: Simplify right side
    660.68x = 383,590.53
  5. Step 5: Solve for x
    x = 383,590.53/660.68
  6. Step 6: Final answer
    x = 580.60

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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.