Finding the Fourth Proportional to 1,428.69, 1,971.57 and 799.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.69 : 1,971.57 = 799.21 : x
2. Step 2: Convert to fraction form
   1,428.69/1,971.57 = 799.21/x
3. Step 3: Cross multiply
   1,428.69x = 1,971.57 × 799.21
4. Step 4: Simplify right side
   1,428.69x = 1,575,688.60
5. Step 5: Solve for x
   x = 1,575,688.60/1,428.69
6. Step 6: Final answer
   x = 1,102.89