Finding the Fourth Proportional to 1,387.71, 1,915.29 and 828.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.71 : 1,915.29 = 828.47 : x
2. Step 2: Convert to fraction form
   1,387.71/1,915.29 = 828.47/x
3. Step 3: Cross multiply
   1,387.71x = 1,915.29 × 828.47
4. Step 4: Simplify right side
   1,387.71x = 1,586,760.31
5. Step 5: Solve for x
   x = 1,586,760.31/1,387.71
6. Step 6: Final answer
   x = 1,143.44