Finding the Fourth Proportional to 2,105.65, 2,905.91 and 1,221.67

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.65 : 2,905.91 = 1,221.67 : x
2. Step 2: Convert to fraction form
   2,105.65/2,905.91 = 1,221.67/x
3. Step 3: Cross multiply
   2,105.65x = 2,905.91 × 1,221.67
4. Step 4: Simplify right side
   2,105.65x = 3,550,063.07
5. Step 5: Solve for x
   x = 3,550,063.07/2,105.65
6. Step 6: Final answer
   x = 1,685.97