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Finding the Fourth Proportional to 413.78, 620.57 and 139.87

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Solution

The fourth proportional to 413.78, 620.57 and 139.87 is: 209.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    413.78 : 620.57 = 139.87 : x
  2. Step 2: Convert to fraction form
    413.78/620.57 = 139.87/x
  3. Step 3: Cross multiply
    413.78x = 620.57 × 139.87
  4. Step 4: Simplify right side
    413.78x = 86,795.67
  5. Step 5: Solve for x
    x = 86,795.67/413.78
  6. Step 6: Final answer
    x = 209.76

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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.