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Finding the Fourth Proportional to 423.12, 630.78 and 388.56

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Solution

The fourth proportional to 423.12, 630.78 and 388.56 is: 579.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    423.12 : 630.78 = 388.56 : x
  2. Step 2: Convert to fraction form
    423.12/630.78 = 388.56/x
  3. Step 3: Cross multiply
    423.12x = 630.78 × 388.56
  4. Step 4: Simplify right side
    423.12x = 245,095.88
  5. Step 5: Solve for x
    x = 245,095.88/423.12
  6. Step 6: Final answer
    x = 579.26

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.