Finding the Fourth Proportional to 2,086.81, 3,131.06 and 916.21

Step by Step Solution

1. Step 1: Write the proportion equation
   2,086.81 : 3,131.06 = 916.21 : x
2. Step 2: Convert to fraction form
   2,086.81/3,131.06 = 916.21/x
3. Step 3: Cross multiply
   2,086.81x = 3,131.06 × 916.21
4. Step 4: Simplify right side
   2,086.81x = 2,868,707.82
5. Step 5: Solve for x
   x = 2,868,707.82/2,086.81
6. Step 6: Final answer
   x = 1,374.68