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Finding the Fourth Proportional to 1,413.78, 2,120.67 and 387.78

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Solution

The fourth proportional to 1,413.78, 2,120.67 and 387.78 is: 581.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,413.78 : 2,120.67 = 387.78 : x
  2. Step 2: Convert to fraction form
    1,413.78/2,120.67 = 387.78/x
  3. Step 3: Cross multiply
    1,413.78x = 2,120.67 × 387.78
  4. Step 4: Simplify right side
    1,413.78x = 822,353.41
  5. Step 5: Solve for x
    x = 822,353.41/1,413.78
  6. Step 6: Final answer
    x = 581.67

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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.