Finding the Fourth Proportional to 1,428.38, 1,969.81 and 931.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.38 : 1,969.81 = 931.40 : x
2. Step 2: Convert to fraction form
   1,428.38/1,969.81 = 931.40/x
3. Step 3: Cross multiply
   1,428.38x = 1,969.81 × 931.40
4. Step 4: Simplify right side
   1,428.38x = 1,834,668.86
5. Step 5: Solve for x
   x = 1,834,668.86/1,428.38
6. Step 6: Final answer
   x = 1,284.44