Finding the Fourth Proportional to 1,388.16, 1,914.96 and 828.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.16 : 1,914.96 = 828.24 : x
2. Step 2: Convert to fraction form
   1,388.16/1,914.96 = 828.24/x
3. Step 3: Cross multiply
   1,388.16x = 1,914.96 × 828.24
4. Step 4: Simplify right side
   1,388.16x = 1,586,046.47
5. Step 5: Solve for x
   x = 1,586,046.47/1,388.16
6. Step 6: Final answer
   x = 1,142.55