Finding the Fourth Proportional to 1,428.17, 1,971.47 and 931.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.17 : 1,971.47 = 931.23 : x
2. Step 2: Convert to fraction form
   1,428.17/1,971.47 = 931.23/x
3. Step 3: Cross multiply
   1,428.17x = 1,971.47 × 931.23
4. Step 4: Simplify right side
   1,428.17x = 1,835,894.34
5. Step 5: Solve for x
   x = 1,835,894.34/1,428.17
6. Step 6: Final answer
   x = 1,285.49