Finding the Fourth Proportional to 2,631.48, 3,945.42 and 987.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,631.48 : 3,945.42 = 987.72 : x
2. Step 2: Convert to fraction form
   2,631.48/3,945.42 = 987.72/x
3. Step 3: Cross multiply
   2,631.48x = 3,945.42 × 987.72
4. Step 4: Simplify right side
   2,631.48x = 3,896,970.24
5. Step 5: Solve for x
   x = 3,896,970.24/2,631.48
6. Step 6: Final answer
   x = 1,480.90