Finding the Fourth Proportional to 1,258.16, 1,879.79 and 1,215.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,258.16 : 1,879.79 = 1,215.10 : x
2. Step 2: Convert to fraction form
   1,258.16/1,879.79 = 1,215.10/x
3. Step 3: Cross multiply
   1,258.16x = 1,879.79 × 1,215.10
4. Step 4: Simplify right side
   1,258.16x = 2,284,132.83
5. Step 5: Solve for x
   x = 2,284,132.83/1,258.16
6. Step 6: Final answer
   x = 1,815.45