Finding the Fourth Proportional to 1,915.20, 2,870.76 and 1,091.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,915.20 : 2,870.76 = 1,091.70 : x
2. Step 2: Convert to fraction form
   1,915.20/2,870.76 = 1,091.70/x
3. Step 3: Cross multiply
   1,915.20x = 2,870.76 × 1,091.70
4. Step 4: Simplify right side
   1,915.20x = 3,134,019.32
5. Step 5: Solve for x
   x = 3,134,019.32/1,915.20
6. Step 6: Final answer
   x = 1,636.39