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Finding the Fourth Proportional to 660.91, 991.34 and 386.79

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Solution

The fourth proportional to 660.91, 991.34 and 386.79 is: 580.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.91 : 991.34 = 386.79 : x
  2. Step 2: Convert to fraction form
    660.91/991.34 = 386.79/x
  3. Step 3: Cross multiply
    660.91x = 991.34 × 386.79
  4. Step 4: Simplify right side
    660.91x = 383,440.40
  5. Step 5: Solve for x
    x = 383,440.40/660.91
  6. Step 6: Final answer
    x = 580.17

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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.