Finding the Fourth Proportional to 1,111.20, 1,668.24 and 678.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.20 : 1,668.24 = 678.96 : x
2. Step 2: Convert to fraction form
   1,111.20/1,668.24 = 678.96/x
3. Step 3: Cross multiply
   1,111.20x = 1,668.24 × 678.96
4. Step 4: Simplify right side
   1,111.20x = 1,132,668.23
5. Step 5: Solve for x
   x = 1,132,668.23/1,111.20
6. Step 6: Final answer
   x = 1,019.32