Finding the Fourth Proportional to 2,128.65, 2,931.45 and 1,538.25

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.65 : 2,931.45 = 1,538.25 : x
2. Step 2: Convert to fraction form
   2,128.65/2,931.45 = 1,538.25/x
3. Step 3: Cross multiply
   2,128.65x = 2,931.45 × 1,538.25
4. Step 4: Simplify right side
   2,128.65x = 4,509,302.96
5. Step 5: Solve for x
   x = 4,509,302.96/2,128.65
6. Step 6: Final answer
   x = 2,118.39