Finding the Fourth Proportional to 1,387.61, 1,914.73 and 916.49

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.61 : 1,914.73 = 916.49 : x
2. Step 2: Convert to fraction form
   1,387.61/1,914.73 = 916.49/x
3. Step 3: Cross multiply
   1,387.61x = 1,914.73 × 916.49
4. Step 4: Simplify right side
   1,387.61x = 1,754,826.72
5. Step 5: Solve for x
   x = 1,754,826.72/1,387.61
6. Step 6: Final answer
   x = 1,264.64