Finding the Fourth Proportional to 2,116.50, 2,920.80 and 1,172.31

Step by Step Solution

1. Step 1: Write the proportion equation
   2,116.50 : 2,920.80 = 1,172.31 : x
2. Step 2: Convert to fraction form
   2,116.50/2,920.80 = 1,172.31/x
3. Step 3: Cross multiply
   2,116.50x = 2,920.80 × 1,172.31
4. Step 4: Simplify right side
   2,116.50x = 3,424,077.19
5. Step 5: Solve for x
   x = 3,424,077.19/2,116.50
6. Step 6: Final answer
   x = 1,617.80