Finding the Fourth Proportional to 1,389.15, 1,916.71 and 829.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.15 : 1,916.71 = 829.80 : x
2. Step 2: Convert to fraction form
   1,389.15/1,916.71 = 829.80/x
3. Step 3: Cross multiply
   1,389.15x = 1,916.71 × 829.80
4. Step 4: Simplify right side
   1,389.15x = 1,590,485.96
5. Step 5: Solve for x
   x = 1,590,485.96/1,389.15
6. Step 6: Final answer
   x = 1,144.93