Finding the Fourth Proportional to 1,188.05, 1,639.61 and 690.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.05 : 1,639.61 = 690.72 : x
2. Step 2: Convert to fraction form
   1,188.05/1,639.61 = 690.72/x
3. Step 3: Cross multiply
   1,188.05x = 1,639.61 × 690.72
4. Step 4: Simplify right side
   1,188.05x = 1,132,522.13
5. Step 5: Solve for x
   x = 1,132,522.13/1,188.05
6. Step 6: Final answer
   x = 953.26