Finding the Fourth Proportional to 1,089.60, 1,506.24 and 870.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,089.60 : 1,506.24 = 870.72 : x
2. Step 2: Convert to fraction form
   1,089.60/1,506.24 = 870.72/x
3. Step 3: Cross multiply
   1,089.60x = 1,506.24 × 870.72
4. Step 4: Simplify right side
   1,089.60x = 1,311,513.29
5. Step 5: Solve for x
   x = 1,311,513.29/1,089.60
6. Step 6: Final answer
   x = 1,203.66