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Finding the Fourth Proportional to 660.90, 990.20 and 426.66

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Solution

The fourth proportional to 660.90, 990.20 and 426.66 is: 639.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.90 : 990.20 = 426.66 : x
  2. Step 2: Convert to fraction form
    660.90/990.20 = 426.66/x
  3. Step 3: Cross multiply
    660.90x = 990.20 × 426.66
  4. Step 4: Simplify right side
    660.90x = 422,478.73
  5. Step 5: Solve for x
    x = 422,478.73/660.90
  6. Step 6: Final answer
    x = 639.25

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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.