Finding the Fourth Proportional to 1,290.78, 1,780.74 and 848.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.78 : 1,780.74 = 848.10 : x
2. Step 2: Convert to fraction form
   1,290.78/1,780.74 = 848.10/x
3. Step 3: Cross multiply
   1,290.78x = 1,780.74 × 848.10
4. Step 4: Simplify right side
   1,290.78x = 1,510,245.59
5. Step 5: Solve for x
   x = 1,510,245.59/1,290.78
6. Step 6: Final answer
   x = 1,170.03