Finding the Fourth Proportional to 1,275.89, 1,915.12 and 859.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,275.89 : 1,915.12 = 859.37 : x
2. Step 2: Convert to fraction form
   1,275.89/1,915.12 = 859.37/x
3. Step 3: Cross multiply
   1,275.89x = 1,915.12 × 859.37
4. Step 4: Simplify right side
   1,275.89x = 1,645,796.67
5. Step 5: Solve for x
   x = 1,645,796.67/1,275.89
6. Step 6: Final answer
   x = 1,289.92