Finding the Fourth Proportional to 1,386.72, 1,914.84 and 1,155.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.72 : 1,914.84 = 1,155.06 : x
2. Step 2: Convert to fraction form
   1,386.72/1,914.84 = 1,155.06/x
3. Step 3: Cross multiply
   1,386.72x = 1,914.84 × 1,155.06
4. Step 4: Simplify right side
   1,386.72x = 2,211,755.09
5. Step 5: Solve for x
   x = 2,211,755.09/1,386.72
6. Step 6: Final answer
   x = 1,594.95