Finding the Fourth Proportional to 1,288.91, 1,780.17 and 848.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.91 : 1,780.17 = 848.78 : x
2. Step 2: Convert to fraction form
   1,288.91/1,780.17 = 848.78/x
3. Step 3: Cross multiply
   1,288.91x = 1,780.17 × 848.78
4. Step 4: Simplify right side
   1,288.91x = 1,510,972.69
5. Step 5: Solve for x
   x = 1,510,972.69/1,288.91
6. Step 6: Final answer
   x = 1,172.29