Finding the Fourth Proportional to 1,387.75, 1,914.76 and 828.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.75 : 1,914.76 = 828.39 : x
2. Step 2: Convert to fraction form
   1,387.75/1,914.76 = 828.39/x
3. Step 3: Cross multiply
   1,387.75x = 1,914.76 × 828.39
4. Step 4: Simplify right side
   1,387.75x = 1,586,168.04
5. Step 5: Solve for x
   x = 1,586,168.04/1,387.75
6. Step 6: Final answer
   x = 1,142.98