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Finding the Fourth Proportional to 427.20, 643.48 and 388.92

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Solution

The fourth proportional to 427.20, 643.48 and 388.92 is: 585.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.20 : 643.48 = 388.92 : x
  2. Step 2: Convert to fraction form
    427.20/643.48 = 388.92/x
  3. Step 3: Cross multiply
    427.20x = 643.48 × 388.92
  4. Step 4: Simplify right side
    427.20x = 250,262.24
  5. Step 5: Solve for x
    x = 250,262.24/427.20
  6. Step 6: Final answer
    x = 585.82

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.