Finding the Fourth Proportional to 2,071.78, 3,106.76 and 665.86

Step by Step Solution

1. Step 1: Write the proportion equation
   2,071.78 : 3,106.76 = 665.86 : x
2. Step 2: Convert to fraction form
   2,071.78/3,106.76 = 665.86/x
3. Step 3: Cross multiply
   2,071.78x = 3,106.76 × 665.86
4. Step 4: Simplify right side
   2,071.78x = 2,068,648.35
5. Step 5: Solve for x
   x = 2,068,648.35/2,071.78
6. Step 6: Final answer
   x = 998.49