Finding the Fourth Proportional to 1,069.40, 1,603.56 and 678.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,069.40 : 1,603.56 = 678.72 : x
2. Step 2: Convert to fraction form
   1,069.40/1,603.56 = 678.72/x
3. Step 3: Cross multiply
   1,069.40x = 1,603.56 × 678.72
4. Step 4: Simplify right side
   1,069.40x = 1,088,368.24
5. Step 5: Solve for x
   x = 1,088,368.24/1,069.40
6. Step 6: Final answer
   x = 1,017.74