Finding the Fourth Proportional to 1,321.31, 1,979.34 and 800.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.31 : 1,979.34 = 800.99 : x
2. Step 2: Convert to fraction form
   1,321.31/1,979.34 = 800.99/x
3. Step 3: Cross multiply
   1,321.31x = 1,979.34 × 800.99
4. Step 4: Simplify right side
   1,321.31x = 1,585,426.07
5. Step 5: Solve for x
   x = 1,585,426.07/1,321.31
6. Step 6: Final answer
   x = 1,199.89