Finding the Fourth Proportional to 1,017.71, 1,411.63 and 990.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,017.71 : 1,411.63 = 990.71 : x
2. Step 2: Convert to fraction form
   1,017.71/1,411.63 = 990.71/x
3. Step 3: Cross multiply
   1,017.71x = 1,411.63 × 990.71
4. Step 4: Simplify right side
   1,017.71x = 1,398,511.72
5. Step 5: Solve for x
   x = 1,398,511.72/1,017.71
6. Step 6: Final answer
   x = 1,374.17