Finding the Fourth Proportional to 2,186.79, 3,018.86 and 1,390.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,186.79 : 3,018.86 = 1,390.91 : x
2. Step 2: Convert to fraction form
   2,186.79/3,018.86 = 1,390.91/x
3. Step 3: Cross multiply
   2,186.79x = 3,018.86 × 1,390.91
4. Step 4: Simplify right side
   2,186.79x = 4,198,940.51
5. Step 5: Solve for x
   x = 4,198,940.51/2,186.79
6. Step 6: Final answer
   x = 1,920.14