Finding the Fourth Proportional to 3,913.68, 5,870.86 and 991.98

Step by Step Solution

1. Step 1: Write the proportion equation
   3,913.68 : 5,870.86 = 991.98 : x
2. Step 2: Convert to fraction form
   3,913.68/5,870.86 = 991.98/x
3. Step 3: Cross multiply
   3,913.68x = 5,870.86 × 991.98
4. Step 4: Simplify right side
   3,913.68x = 5,823,775.70
5. Step 5: Solve for x
   x = 5,823,775.70/3,913.68
6. Step 6: Final answer
   x = 1,488.06