Finding the Fourth Proportional to 1,428.38, 1,971.16 and 931.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.38 : 1,971.16 = 931.86 : x
2. Step 2: Convert to fraction form
   1,428.38/1,971.16 = 931.86/x
3. Step 3: Cross multiply
   1,428.38x = 1,971.16 × 931.86
4. Step 4: Simplify right side
   1,428.38x = 1,836,835.44
5. Step 5: Solve for x
   x = 1,836,835.44/1,428.38
6. Step 6: Final answer
   x = 1,285.96