Finding the Fourth Proportional to 1,428.24, 1,971.78 and 986.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.24 : 1,971.78 = 986.79 : x
2. Step 2: Convert to fraction form
   1,428.24/1,971.78 = 986.79/x
3. Step 3: Cross multiply
   1,428.24x = 1,971.78 × 986.79
4. Step 4: Simplify right side
   1,428.24x = 1,945,732.79
5. Step 5: Solve for x
   x = 1,945,732.79/1,428.24
6. Step 6: Final answer
   x = 1,362.33