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Finding the Fourth Proportional to 660.78, 990.36 and 478.80

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Solution

The fourth proportional to 660.78, 990.36 and 478.80 is: 717.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.78 : 990.36 = 478.80 : x
  2. Step 2: Convert to fraction form
    660.78/990.36 = 478.80/x
  3. Step 3: Cross multiply
    660.78x = 990.36 × 478.80
  4. Step 4: Simplify right side
    660.78x = 474,184.37
  5. Step 5: Solve for x
    x = 474,184.37/660.78
  6. Step 6: Final answer
    x = 717.61

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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.