Finding the Fourth Proportional to 1,171.76, 1,617.72 and 779.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,171.76 : 1,617.72 = 779.60 : x
2. Step 2: Convert to fraction form
   1,171.76/1,617.72 = 779.60/x
3. Step 3: Cross multiply
   1,171.76x = 1,617.72 × 779.60
4. Step 4: Simplify right side
   1,171.76x = 1,261,174.51
5. Step 5: Solve for x
   x = 1,261,174.51/1,171.76
6. Step 6: Final answer
   x = 1,076.31