Finding the Fourth Proportional to 2,087.16, 3,128.04 and 991.86

Step by Step Solution

1. Step 1: Write the proportion equation
   2,087.16 : 3,128.04 = 991.86 : x
2. Step 2: Convert to fraction form
   2,087.16/3,128.04 = 991.86/x
3. Step 3: Cross multiply
   2,087.16x = 3,128.04 × 991.86
4. Step 4: Simplify right side
   2,087.16x = 3,102,577.75
5. Step 5: Solve for x
   x = 3,102,577.75/2,087.16
6. Step 6: Final answer
   x = 1,486.51