Finding the Fourth Proportional to 1,191.16, 1,643.79 and 667.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,191.16 : 1,643.79 = 667.20 : x
2. Step 2: Convert to fraction form
   1,191.16/1,643.79 = 667.20/x
3. Step 3: Cross multiply
   1,191.16x = 1,643.79 × 667.20
4. Step 4: Simplify right side
   1,191.16x = 1,096,736.69
5. Step 5: Solve for x
   x = 1,096,736.69/1,191.16
6. Step 6: Final answer
   x = 920.73