Finding the Fourth Proportional to 2,111.68, 3,165.91 and 1,278.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,111.68 : 3,165.91 = 1,278.57 : x
2. Step 2: Convert to fraction form
   2,111.68/3,165.91 = 1,278.57/x
3. Step 3: Cross multiply
   2,111.68x = 3,165.91 × 1,278.57
4. Step 4: Simplify right side
   2,111.68x = 4,047,823.32
5. Step 5: Solve for x
   x = 4,047,823.32/2,111.68
6. Step 6: Final answer
   x = 1,916.87