Finding the Fourth Proportional to 1,185.90, 1,636.72 and 688.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,185.90 : 1,636.72 = 688.70 : x
2. Step 2: Convert to fraction form
   1,185.90/1,636.72 = 688.70/x
3. Step 3: Cross multiply
   1,185.90x = 1,636.72 × 688.70
4. Step 4: Simplify right side
   1,185.90x = 1,127,209.06
5. Step 5: Solve for x
   x = 1,127,209.06/1,185.90
6. Step 6: Final answer
   x = 950.51