Finding the Fourth Proportional to 1,061.34, 1,591.76 and 320.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,061.34 : 1,591.76 = 320.80 : x
2. Step 2: Convert to fraction form
   1,061.34/1,591.76 = 320.80/x
3. Step 3: Cross multiply
   1,061.34x = 1,591.76 × 320.80
4. Step 4: Simplify right side
   1,061.34x = 510,636.61
5. Step 5: Solve for x
   x = 510,636.61/1,061.34
6. Step 6: Final answer
   x = 481.12