Finding the Third Proportional to 390.94 and 915.56

Step by Step Solution

1. Step 1: Write the proportion equation
   390.94 : 915.56 = 915.56 : x
2. Step 2: Convert to fraction form
   390.94/915.56 = 915.56/x
3. Step 3: Cross multiply
   390.94x = 915.56 × 915.56
4. Step 4: Simplify right side
   390.94x = 838,254.69
5. Step 5: Solve for x
   x = 838,254.69/390.94
6. Step 6: Final answer
   x = 2,144.22