Finding the Fourth Proportional to 2,215.12, 3,321.86 and 915.88

Step by Step Solution

1. Step 1: Write the proportion equation
   2,215.12 : 3,321.86 = 915.88 : x
2. Step 2: Convert to fraction form
   2,215.12/3,321.86 = 915.88/x
3. Step 3: Cross multiply
   2,215.12x = 3,321.86 × 915.88
4. Step 4: Simplify right side
   2,215.12x = 3,042,408.53
5. Step 5: Solve for x
   x = 3,042,408.53/2,215.12
6. Step 6: Final answer
   x = 1,373.48