Finding the Fourth Proportional to 2,086.63, 3,131.16 and 991.51

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.63 : 3,131.16 = 991.51 : x
2. Step 2: Convert to fraction form
   2,086.63/3,131.16 = 991.51/x
3. Step 3: Cross multiply
   2,086.63x = 3,131.16 × 991.51
4. Step 4: Simplify right side
   2,086.63x = 3,104,576.45
5. Step 5: Solve for x
   x = 3,104,576.45/2,086.63
6. Step 6: Final answer
   x = 1,487.84