Finding the Fourth Proportional to 1,386.40, 1,911.36 and 961.08

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.40 : 1,911.36 = 961.08 : x
2. Step 2: Convert to fraction form
   1,386.40/1,911.36 = 961.08/x
3. Step 3: Cross multiply
   1,386.40x = 1,911.36 × 961.08
4. Step 4: Simplify right side
   1,386.40x = 1,836,969.87
5. Step 5: Solve for x
   x = 1,836,969.87/1,386.40
6. Step 6: Final answer
   x = 1,324.99