Finding the Fourth Proportional to 1,388.37, 1,915.28 and 916.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.37 : 1,915.28 = 916.45 : x
2. Step 2: Convert to fraction form
   1,388.37/1,915.28 = 916.45/x
3. Step 3: Cross multiply
   1,388.37x = 1,915.28 × 916.45
4. Step 4: Simplify right side
   1,388.37x = 1,755,252.42
5. Step 5: Solve for x
   x = 1,755,252.42/1,388.37
6. Step 6: Final answer
   x = 1,264.25