Finding the Fourth Proportional to 1,128.21, 1,556.82 and 686.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.21 : 1,556.82 = 686.14 : x
2. Step 2: Convert to fraction form
   1,128.21/1,556.82 = 686.14/x
3. Step 3: Cross multiply
   1,128.21x = 1,556.82 × 686.14
4. Step 4: Simplify right side
   1,128.21x = 1,068,196.47
5. Step 5: Solve for x
   x = 1,068,196.47/1,128.21
6. Step 6: Final answer
   x = 946.81