Finding the Fourth Proportional to 2,145.80, 3,218.86 and 913.08

Step by Step Solution

1. Step 1: Write the proportion equation
   2,145.80 : 3,218.86 = 913.08 : x
2. Step 2: Convert to fraction form
   2,145.80/3,218.86 = 913.08/x
3. Step 3: Cross multiply
   2,145.80x = 3,218.86 × 913.08
4. Step 4: Simplify right side
   2,145.80x = 2,939,076.69
5. Step 5: Solve for x
   x = 2,939,076.69/2,145.80
6. Step 6: Final answer
   x = 1,369.69