Finding the Fourth Proportional to 2,085, 3,128.70 and 930.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,085 : 3,128.70 = 930.78 : x
2. Step 2: Convert to fraction form
   2,085/3,128.70 = 930.78/x
3. Step 3: Cross multiply
   2,085x = 3,128.70 × 930.78
4. Step 4: Simplify right side
   2,085x = 2,912,131.39
5. Step 5: Solve for x
   x = 2,912,131.39/2,085
6. Step 6: Final answer
   x = 1,396.71