Finding the Fourth Proportional to 1,387.82, 1,915.46 and 891.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.82 : 1,915.46 = 891.09 : x
2. Step 2: Convert to fraction form
   1,387.82/1,915.46 = 891.09/x
3. Step 3: Cross multiply
   1,387.82x = 1,915.46 × 891.09
4. Step 4: Simplify right side
   1,387.82x = 1,706,847.25
5. Step 5: Solve for x
   x = 1,706,847.25/1,387.82
6. Step 6: Final answer
   x = 1,229.88