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Finding the Fourth Proportional to 388.71, 583.13 and 128.72

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Solution

The fourth proportional to 388.71, 583.13 and 128.72 is: 193.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    388.71 : 583.13 = 128.72 : x
  2. Step 2: Convert to fraction form
    388.71/583.13 = 128.72/x
  3. Step 3: Cross multiply
    388.71x = 583.13 × 128.72
  4. Step 4: Simplify right side
    388.71x = 75,061.79
  5. Step 5: Solve for x
    x = 75,061.79/388.71
  6. Step 6: Final answer
    x = 193.11

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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.