Finding the Fourth Proportional to 2,645.76, 3,970.24 and 915.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,645.76 : 3,970.24 = 915.60 : x
2. Step 2: Convert to fraction form
   2,645.76/3,970.24 = 915.60/x
3. Step 3: Cross multiply
   2,645.76x = 3,970.24 × 915.60
4. Step 4: Simplify right side
   2,645.76x = 3,635,151.74
5. Step 5: Solve for x
   x = 3,635,151.74/2,645.76
6. Step 6: Final answer
   x = 1,373.95