Finding the Fourth Proportional to 2,086.56, 3,128.93 and 991.24

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.56 : 3,128.93 = 991.24 : x
2. Step 2: Convert to fraction form
   2,086.56/3,128.93 = 991.24/x
3. Step 3: Cross multiply
   2,086.56x = 3,128.93 × 991.24
4. Step 4: Simplify right side
   2,086.56x = 3,101,520.57
5. Step 5: Solve for x
   x = 3,101,520.57/2,086.56
6. Step 6: Final answer
   x = 1,486.43