Finding the Fourth Proportional to 2,213.91, 3,320.88 and 915.36

Step by Step Solution

1. Step 1: Write the proportion equation
   2,213.91 : 3,320.88 = 915.36 : x
2. Step 2: Convert to fraction form
   2,213.91/3,320.88 = 915.36/x
3. Step 3: Cross multiply
   2,213.91x = 3,320.88 × 915.36
4. Step 4: Simplify right side
   2,213.91x = 3,039,800.72
5. Step 5: Solve for x
   x = 3,039,800.72/2,213.91
6. Step 6: Final answer
   x = 1,373.05