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Finding the Fourth Proportional to 390.90, 583.31 and 388.20

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Solution

The fourth proportional to 390.90, 583.31 and 388.20 is: 579.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.90 : 583.31 = 388.20 : x
  2. Step 2: Convert to fraction form
    390.90/583.31 = 388.20/x
  3. Step 3: Cross multiply
    390.90x = 583.31 × 388.20
  4. Step 4: Simplify right side
    390.90x = 226,439.00
  5. Step 5: Solve for x
    x = 226,439.00/390.90
  6. Step 6: Final answer
    x = 579.28

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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.