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Finding the Fourth Proportional to 1,278.86, 1,918.56 and 413.78

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Solution

The fourth proportional to 1,278.86, 1,918.56 and 413.78 is: 620.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.86 : 1,918.56 = 413.78 : x
  2. Step 2: Convert to fraction form
    1,278.86/1,918.56 = 413.78/x
  3. Step 3: Cross multiply
    1,278.86x = 1,918.56 × 413.78
  4. Step 4: Simplify right side
    1,278.86x = 793,861.76
  5. Step 5: Solve for x
    x = 793,861.76/1,278.86
  6. Step 6: Final answer
    x = 620.76

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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.