Finding the Fourth Proportional to 2,166.72, 2,990.07 and 1,172.01

Step by Step Solution

1. Step 1: Write the proportion equation
   2,166.72 : 2,990.07 = 1,172.01 : x
2. Step 2: Convert to fraction form
   2,166.72/2,990.07 = 1,172.01/x
3. Step 3: Cross multiply
   2,166.72x = 2,990.07 × 1,172.01
4. Step 4: Simplify right side
   2,166.72x = 3,504,388.71
5. Step 5: Solve for x
   x = 3,504,388.71/2,166.72
6. Step 6: Final answer
   x = 1,617.37