Finding the Fourth Proportional to 1,399.77, 1,931.79 and 840.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.77 : 1,931.79 = 840.23 : x
2. Step 2: Convert to fraction form
   1,399.77/1,931.79 = 840.23/x
3. Step 3: Cross multiply
   1,399.77x = 1,931.79 × 840.23
4. Step 4: Simplify right side
   1,399.77x = 1,623,147.91
5. Step 5: Solve for x
   x = 1,623,147.91/1,399.77
6. Step 6: Final answer
   x = 1,159.58