Finding the Fourth Proportional to 1,419.10, 2,128.71 and 445.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.10 : 2,128.71 = 445.21 : x
2. Step 2: Convert to fraction form
   1,419.10/2,128.71 = 445.21/x
3. Step 3: Cross multiply
   1,419.10x = 2,128.71 × 445.21
4. Step 4: Simplify right side
   1,419.10x = 947,722.98
5. Step 5: Solve for x
   x = 947,722.98/1,419.10
6. Step 6: Final answer
   x = 667.83