Finding the Fourth Proportional to 2,112.01, 3,172.58 and 1,290.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,112.01 : 3,172.58 = 1,290.78 : x
2. Step 2: Convert to fraction form
   2,112.01/3,172.58 = 1,290.78/x
3. Step 3: Cross multiply
   2,112.01x = 3,172.58 × 1,290.78
4. Step 4: Simplify right side
   2,112.01x = 4,095,088.43
5. Step 5: Solve for x
   x = 4,095,088.43/2,112.01
6. Step 6: Final answer
   x = 1,938.96