Finding the Fourth Proportional to 2,142.65, 2,956.80 and 1,211.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,142.65 : 2,956.80 = 1,211.15 : x
2. Step 2: Convert to fraction form
   2,142.65/2,956.80 = 1,211.15/x
3. Step 3: Cross multiply
   2,142.65x = 2,956.80 × 1,211.15
4. Step 4: Simplify right side
   2,142.65x = 3,581,128.32
5. Step 5: Solve for x
   x = 3,581,128.32/2,142.65
6. Step 6: Final answer
   x = 1,671.35