Finding the Fourth Proportional to 1,433.28, 1,978.08 and 990.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,433.28 : 1,978.08 = 990.24 : x
2. Step 2: Convert to fraction form
   1,433.28/1,978.08 = 990.24/x
3. Step 3: Cross multiply
   1,433.28x = 1,978.08 × 990.24
4. Step 4: Simplify right side
   1,433.28x = 1,958,773.94
5. Step 5: Solve for x
   x = 1,958,773.94/1,433.28
6. Step 6: Final answer
   x = 1,366.64