Finding the Fourth Proportional to 2,160.88, 3,243.34 and 991.51

Step by Step Solution

1. Step 1: Write the proportion equation
   2,160.88 : 3,243.34 = 991.51 : x
2. Step 2: Convert to fraction form
   2,160.88/3,243.34 = 991.51/x
3. Step 3: Cross multiply
   2,160.88x = 3,243.34 × 991.51
4. Step 4: Simplify right side
   2,160.88x = 3,215,804.04
5. Step 5: Solve for x
   x = 3,215,804.04/2,160.88
6. Step 6: Final answer
   x = 1,488.19