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Finding the Fourth Proportional to 388.12, 582.21 and 128.11

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Solution

The fourth proportional to 388.12, 582.21 and 128.11 is: 192.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    388.12 : 582.21 = 128.11 : x
  2. Step 2: Convert to fraction form
    388.12/582.21 = 128.11/x
  3. Step 3: Cross multiply
    388.12x = 582.21 × 128.11
  4. Step 4: Simplify right side
    388.12x = 74,586.20
  5. Step 5: Solve for x
    x = 74,586.20/388.12
  6. Step 6: Final answer
    x = 192.17

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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.