Finding the Fourth Proportional to 1,185.75, 1,636.28 and 688.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,185.75 : 1,636.28 = 688.31 : x
2. Step 2: Convert to fraction form
   1,185.75/1,636.28 = 688.31/x
3. Step 3: Cross multiply
   1,185.75x = 1,636.28 × 688.31
4. Step 4: Simplify right side
   1,185.75x = 1,126,256.26
5. Step 5: Solve for x
   x = 1,126,256.26/1,185.75
6. Step 6: Final answer
   x = 949.83