Finding the Fourth Proportional to 1,191.09, 1,643.55 and 667.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,191.09 : 1,643.55 = 667.12 : x
2. Step 2: Convert to fraction form
   1,191.09/1,643.55 = 667.12/x
3. Step 3: Cross multiply
   1,191.09x = 1,643.55 × 667.12
4. Step 4: Simplify right side
   1,191.09x = 1,096,445.08
5. Step 5: Solve for x
   x = 1,096,445.08/1,191.09
6. Step 6: Final answer
   x = 920.54