Finding the Fourth Proportional to 1,388.27, 1,915.11 and 828.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.27 : 1,915.11 = 828.56 : x
2. Step 2: Convert to fraction form
   1,388.27/1,915.11 = 828.56/x
3. Step 3: Cross multiply
   1,388.27x = 1,915.11 × 828.56
4. Step 4: Simplify right side
   1,388.27x = 1,586,788.33
5. Step 5: Solve for x
   x = 1,586,788.33/1,388.27
6. Step 6: Final answer
   x = 1,142.99