Finding the Fourth Proportional to 1,131.55, 1,696.15 and 643.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.55 : 1,696.15 = 643.55 : x
2. Step 2: Convert to fraction form
   1,131.55/1,696.15 = 643.55/x
3. Step 3: Cross multiply
   1,131.55x = 1,696.15 × 643.55
4. Step 4: Simplify right side
   1,131.55x = 1,091,559.96
5. Step 5: Solve for x
   x = 1,091,559.96/1,131.55
6. Step 6: Final answer
   x = 964.66