Finding the Fourth Proportional to 1,388.46, 1,915.74 and 864.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.46 : 1,915.74 = 864.12 : x
2. Step 2: Convert to fraction form
   1,388.46/1,915.74 = 864.12/x
3. Step 3: Cross multiply
   1,388.46x = 1,915.74 × 864.12
4. Step 4: Simplify right side
   1,388.46x = 1,655,429.25
5. Step 5: Solve for x
   x = 1,655,429.25/1,388.46
6. Step 6: Final answer
   x = 1,192.28