Finding the Fourth Proportional to 2,128.60, 2,931.42 and 1,538.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.60 : 2,931.42 = 1,538.20 : x
2. Step 2: Convert to fraction form
   2,128.60/2,931.42 = 1,538.20/x
3. Step 3: Cross multiply
   2,128.60x = 2,931.42 × 1,538.20
4. Step 4: Simplify right side
   2,128.60x = 4,509,110.24
5. Step 5: Solve for x
   x = 4,509,110.24/2,128.60
6. Step 6: Final answer
   x = 2,118.35