Finding the Fourth Proportional to 2,286.72, 3,428.88 and 987.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,286.72 : 3,428.88 = 987.60 : x
2. Step 2: Convert to fraction form
   2,286.72/3,428.88 = 987.60/x
3. Step 3: Cross multiply
   2,286.72x = 3,428.88 × 987.60
4. Step 4: Simplify right side
   2,286.72x = 3,386,361.89
5. Step 5: Solve for x
   x = 3,386,361.89/2,286.72
6. Step 6: Final answer
   x = 1,480.88