Finding the Fourth Proportional to 2,100.40, 3,155.10 and 1,279.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,100.40 : 3,155.10 = 1,279.12 : x
2. Step 2: Convert to fraction form
   2,100.40/3,155.10 = 1,279.12/x
3. Step 3: Cross multiply
   2,100.40x = 3,155.10 × 1,279.12
4. Step 4: Simplify right side
   2,100.40x = 4,035,751.51
5. Step 5: Solve for x
   x = 4,035,751.51/2,100.40
6. Step 6: Final answer
   x = 1,921.42