Finding the Fourth Proportional to 1,221.34, 1,684.69 and 801.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,221.34 : 1,684.69 = 801.72 : x
2. Step 2: Convert to fraction form
   1,221.34/1,684.69 = 801.72/x
3. Step 3: Cross multiply
   1,221.34x = 1,684.69 × 801.72
4. Step 4: Simplify right side
   1,221.34x = 1,350,649.67
5. Step 5: Solve for x
   x = 1,350,649.67/1,221.34
6. Step 6: Final answer
   x = 1,105.88