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Finding the Fourth Proportional to 427.88, 640.91 and 389.15

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Solution

The fourth proportional to 427.88, 640.91 and 389.15 is: 582.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.88 : 640.91 = 389.15 : x
  2. Step 2: Convert to fraction form
    427.88/640.91 = 389.15/x
  3. Step 3: Cross multiply
    427.88x = 640.91 × 389.15
  4. Step 4: Simplify right side
    427.88x = 249,413.90
  5. Step 5: Solve for x
    x = 249,413.90/427.88
  6. Step 6: Final answer
    x = 582.90

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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.