Finding the Fourth Proportional to 2,645.72, 3,970.22 and 915.56

Step by Step Solution

1. Step 1: Write the proportion equation
   2,645.72 : 3,970.22 = 915.56 : x
2. Step 2: Convert to fraction form
   2,645.72/3,970.22 = 915.56/x
3. Step 3: Cross multiply
   2,645.72x = 3,970.22 × 915.56
4. Step 4: Simplify right side
   2,645.72x = 3,634,974.62
5. Step 5: Solve for x
   x = 3,634,974.62/2,645.72
6. Step 6: Final answer
   x = 1,373.91