Finding the Fourth Proportional to 1,661.78, 2,293.28 and 915.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,661.78 : 2,293.28 = 915.71 : x
2. Step 2: Convert to fraction form
   1,661.78/2,293.28 = 915.71/x
3. Step 3: Cross multiply
   1,661.78x = 2,293.28 × 915.71
4. Step 4: Simplify right side
   1,661.78x = 2,099,966.82
5. Step 5: Solve for x
   x = 2,099,966.82/1,661.78
6. Step 6: Final answer
   x = 1,263.68