Finding the Fourth Proportional to 1,111.77, 1,665.15 and 916.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.77 : 1,665.15 = 916.31 : x
2. Step 2: Convert to fraction form
   1,111.77/1,665.15 = 916.31/x
3. Step 3: Cross multiply
   1,111.77x = 1,665.15 × 916.31
4. Step 4: Simplify right side
   1,111.77x = 1,525,780.69
5. Step 5: Solve for x
   x = 1,525,780.69/1,111.77
6. Step 6: Final answer
   x = 1,372.39