Finding the Fourth Proportional to 1,191.28, 1,643.94 and 667.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,191.28 : 1,643.94 = 667.31 : x
2. Step 2: Convert to fraction form
   1,191.28/1,643.94 = 667.31/x
3. Step 3: Cross multiply
   1,191.28x = 1,643.94 × 667.31
4. Step 4: Simplify right side
   1,191.28x = 1,097,017.60
5. Step 5: Solve for x
   x = 1,097,017.60/1,191.28
6. Step 6: Final answer
   x = 920.87