Finding the Fourth Proportional to 1,274.89, 1,759.31 and 715.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,274.89 : 1,759.31 = 715.40 : x
2. Step 2: Convert to fraction form
   1,274.89/1,759.31 = 715.40/x
3. Step 3: Cross multiply
   1,274.89x = 1,759.31 × 715.40
4. Step 4: Simplify right side
   1,274.89x = 1,258,610.37
5. Step 5: Solve for x
   x = 1,258,610.37/1,274.89
6. Step 6: Final answer
   x = 987.23