Finding the Fourth Proportional to 1,191.84, 1,788.27 and 643.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,191.84 : 1,788.27 = 643.38 : x
2. Step 2: Convert to fraction form
   1,191.84/1,788.27 = 643.38/x
3. Step 3: Cross multiply
   1,191.84x = 1,788.27 × 643.38
4. Step 4: Simplify right side
   1,191.84x = 1,150,528.03
5. Step 5: Solve for x
   x = 1,150,528.03/1,191.84
6. Step 6: Final answer
   x = 965.34