Finding the Fourth Proportional to 1,389.60, 1,919.48 and 1,111.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.60 : 1,919.48 = 1,111.77 : x
2. Step 2: Convert to fraction form
   1,389.60/1,919.48 = 1,111.77/x
3. Step 3: Cross multiply
   1,389.60x = 1,919.48 × 1,111.77
4. Step 4: Simplify right side
   1,389.60x = 2,134,014.72
5. Step 5: Solve for x
   x = 2,134,014.72/1,389.60
6. Step 6: Final answer
   x = 1,535.70