Finding the Fourth Proportional to 1,112.80, 1,667.52 and 678.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,112.80 : 1,667.52 = 678.88 : x
2. Step 2: Convert to fraction form
   1,112.80/1,667.52 = 678.88/x
3. Step 3: Cross multiply
   1,112.80x = 1,667.52 × 678.88
4. Step 4: Simplify right side
   1,112.80x = 1,132,045.98
5. Step 5: Solve for x
   x = 1,132,045.98/1,112.80
6. Step 6: Final answer
   x = 1,017.30