Finding the Fourth Proportional to 1,428.58, 1,970.76 and 831.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.58 : 1,970.76 = 831.07 : x
2. Step 2: Convert to fraction form
   1,428.58/1,970.76 = 831.07/x
3. Step 3: Cross multiply
   1,428.58x = 1,970.76 × 831.07
4. Step 4: Simplify right side
   1,428.58x = 1,637,839.51
5. Step 5: Solve for x
   x = 1,637,839.51/1,428.58
6. Step 6: Final answer
   x = 1,146.48