Finding the Fourth Proportional to 2,561.76, 3,842.78 and 830.25

Step by Step Solution

1. Step 1: Write the proportion equation
   2,561.76 : 3,842.78 = 830.25 : x
2. Step 2: Convert to fraction form
   2,561.76/3,842.78 = 830.25/x
3. Step 3: Cross multiply
   2,561.76x = 3,842.78 × 830.25
4. Step 4: Simplify right side
   2,561.76x = 3,190,463.94
5. Step 5: Solve for x
   x = 3,190,463.94/2,561.76
6. Step 6: Final answer
   x = 1,245.42