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Finding the Fourth Proportional to 388.30, 582.20 and 128.20

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Solution

The fourth proportional to 388.30, 582.20 and 128.20 is: 192.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    388.30 : 582.20 = 128.20 : x
  2. Step 2: Convert to fraction form
    388.30/582.20 = 128.20/x
  3. Step 3: Cross multiply
    388.30x = 582.20 × 128.20
  4. Step 4: Simplify right side
    388.30x = 74,638.04
  5. Step 5: Solve for x
    x = 74,638.04/388.30
  6. Step 6: Final answer
    x = 192.22

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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.