Finding the Fourth Proportional to 1,431.69, 1,971.03 and 1,231.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,431.69 : 1,971.03 = 1,231.78 : x
2. Step 2: Convert to fraction form
   1,431.69/1,971.03 = 1,231.78/x
3. Step 3: Cross multiply
   1,431.69x = 1,971.03 × 1,231.78
4. Step 4: Simplify right side
   1,431.69x = 2,427,884.26
5. Step 5: Solve for x
   x = 2,427,884.26/1,431.69
6. Step 6: Final answer
   x = 1,695.82