Finding the Fourth Proportional to 1,678.86, 2,516.55 and 1,215.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,678.86 : 2,516.55 = 1,215.50 : x
2. Step 2: Convert to fraction form
   1,678.86/2,516.55 = 1,215.50/x
3. Step 3: Cross multiply
   1,678.86x = 2,516.55 × 1,215.50
4. Step 4: Simplify right side
   1,678.86x = 3,058,853.94
5. Step 5: Solve for x
   x = 3,058,853.94/1,678.86
6. Step 6: Final answer
   x = 1,821.98