Finding the Fourth Proportional to 1,381.68, 1,907.20 and 916.08

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.68 : 1,907.20 = 916.08 : x
2. Step 2: Convert to fraction form
   1,381.68/1,907.20 = 916.08/x
3. Step 3: Cross multiply
   1,381.68x = 1,907.20 × 916.08
4. Step 4: Simplify right side
   1,381.68x = 1,747,147.78
5. Step 5: Solve for x
   x = 1,747,147.78/1,381.68
6. Step 6: Final answer
   x = 1,264.51