Finding the Fourth Proportional to 1,428.27, 1,971.06 and 830.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.27 : 1,971.06 = 830.71 : x
2. Step 2: Convert to fraction form
   1,428.27/1,971.06 = 830.71/x
3. Step 3: Cross multiply
   1,428.27x = 1,971.06 × 830.71
4. Step 4: Simplify right side
   1,428.27x = 1,637,379.25
5. Step 5: Solve for x
   x = 1,637,379.25/1,428.27
6. Step 6: Final answer
   x = 1,146.41