Finding the Fourth Proportional to 2,142.24, 3,212.16 and 987.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,142.24 : 3,212.16 = 987.12 : x
2. Step 2: Convert to fraction form
   2,142.24/3,212.16 = 987.12/x
3. Step 3: Cross multiply
   2,142.24x = 3,212.16 × 987.12
4. Step 4: Simplify right side
   2,142.24x = 3,170,787.38
5. Step 5: Solve for x
   x = 3,170,787.38/2,142.24
6. Step 6: Final answer
   x = 1,480.13