Finding the Fourth Proportional to 1,388.80, 1,916.80 and 829.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.80 : 1,916.80 = 829.30 : x
2. Step 2: Convert to fraction form
   1,388.80/1,916.80 = 829.30/x
3. Step 3: Cross multiply
   1,388.80x = 1,916.80 × 829.30
4. Step 4: Simplify right side
   1,388.80x = 1,589,602.24
5. Step 5: Solve for x
   x = 1,589,602.24/1,388.80
6. Step 6: Final answer
   x = 1,144.59