Finding the Fourth Proportional to 1,428.15, 1,971.49 and 838.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.15 : 1,971.49 = 838.72 : x
2. Step 2: Convert to fraction form
   1,428.15/1,971.49 = 838.72/x
3. Step 3: Cross multiply
   1,428.15x = 1,971.49 × 838.72
4. Step 4: Simplify right side
   1,428.15x = 1,653,523.90
5. Step 5: Solve for x
   x = 1,653,523.90/1,428.15
6. Step 6: Final answer
   x = 1,157.81