Finding the Fourth Proportional to 1,388.07, 1,915.56 and 828.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.07 : 1,915.56 = 828.43 : x
2. Step 2: Convert to fraction form
   1,388.07/1,915.56 = 828.43/x
3. Step 3: Cross multiply
   1,388.07x = 1,915.56 × 828.43
4. Step 4: Simplify right side
   1,388.07x = 1,586,916.46
5. Step 5: Solve for x
   x = 1,586,916.46/1,388.07
6. Step 6: Final answer
   x = 1,143.25