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Finding the Fourth Proportional to 660.81, 991.22 and 388.64

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Solution

The fourth proportional to 660.81, 991.22 and 388.64 is: 582.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    660.81 : 991.22 = 388.64 : x
  2. Step 2: Convert to fraction form
    660.81/991.22 = 388.64/x
  3. Step 3: Cross multiply
    660.81x = 991.22 × 388.64
  4. Step 4: Simplify right side
    660.81x = 385,220.84
  5. Step 5: Solve for x
    x = 385,220.84/660.81
  6. Step 6: Final answer
    x = 582.95

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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.