Finding the Fourth Proportional to 1,111.30, 1,533.26 and 780

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.30 : 1,533.26 = 780 : x
2. Step 2: Convert to fraction form
   1,111.30/1,533.26 = 780/x
3. Step 3: Cross multiply
   1,111.30x = 1,533.26 × 780
4. Step 4: Simplify right side
   1,111.30x = 1,195,942.80
5. Step 5: Solve for x
   x = 1,195,942.80/1,111.30
6. Step 6: Final answer
   x = 1,076.17