Finding the Fourth Proportional to 1,428.78, 1,970.49 and 1,133.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.78 : 1,970.49 = 1,133.55 : x
2. Step 2: Convert to fraction form
   1,428.78/1,970.49 = 1,133.55/x
3. Step 3: Cross multiply
   1,428.78x = 1,970.49 × 1,133.55
4. Step 4: Simplify right side
   1,428.78x = 2,233,648.94
5. Step 5: Solve for x
   x = 2,233,648.94/1,428.78
6. Step 6: Final answer
   x = 1,563.33