Finding the Fourth Proportional to 1,185.78, 1,636.43 and 661.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,185.78 : 1,636.43 = 661.71 : x
2. Step 2: Convert to fraction form
   1,185.78/1,636.43 = 661.71/x
3. Step 3: Cross multiply
   1,185.78x = 1,636.43 × 661.71
4. Step 4: Simplify right side
   1,185.78x = 1,082,838.79
5. Step 5: Solve for x
   x = 1,082,838.79/1,185.78
6. Step 6: Final answer
   x = 913.19