Finding the Fourth Proportional to 2,071.90, 3,106.59 and 820.99

Step by Step Solution

1. Step 1: Write the proportion equation
   2,071.90 : 3,106.59 = 820.99 : x
2. Step 2: Convert to fraction form
   2,071.90/3,106.59 = 820.99/x
3. Step 3: Cross multiply
   2,071.90x = 3,106.59 × 820.99
4. Step 4: Simplify right side
   2,071.90x = 2,550,479.32
5. Step 5: Solve for x
   x = 2,550,479.32/2,071.90
6. Step 6: Final answer
   x = 1,230.99