Finding the Fourth Proportional to 1,428.23, 1,971.39 and 830.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.23 : 1,971.39 = 830.99 : x
2. Step 2: Convert to fraction form
   1,428.23/1,971.39 = 830.99/x
3. Step 3: Cross multiply
   1,428.23x = 1,971.39 × 830.99
4. Step 4: Simplify right side
   1,428.23x = 1,638,195.52
5. Step 5: Solve for x
   x = 1,638,195.52/1,428.23
6. Step 6: Final answer
   x = 1,147.02