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Finding the Fourth Proportional to 660.76, 990.90 and 388.60

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Solution

The fourth proportional to 660.76, 990.90 and 388.60 is: 582.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.76 : 990.90 = 388.60 : x
  2. Step 2: Convert to fraction form
    660.76/990.90 = 388.60/x
  3. Step 3: Cross multiply
    660.76x = 990.90 × 388.60
  4. Step 4: Simplify right side
    660.76x = 385,063.74
  5. Step 5: Solve for x
    x = 385,063.74/660.76
  6. Step 6: Final answer
    x = 582.76

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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.