Finding the Fourth Proportional to 1,419.31, 2,128.89 and 445.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.31 : 2,128.89 = 445.30 : x
2. Step 2: Convert to fraction form
   1,419.31/2,128.89 = 445.30/x
3. Step 3: Cross multiply
   1,419.31x = 2,128.89 × 445.30
4. Step 4: Simplify right side
   1,419.31x = 947,994.72
5. Step 5: Solve for x
   x = 947,994.72/1,419.31
6. Step 6: Final answer
   x = 667.93