Finding the Fourth Proportional to 1,381.68, 2,071.98 and 688.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.68 : 2,071.98 = 688.12 : x
2. Step 2: Convert to fraction form
   1,381.68/2,071.98 = 688.12/x
3. Step 3: Cross multiply
   1,381.68x = 2,071.98 × 688.12
4. Step 4: Simplify right side
   1,381.68x = 1,425,770.88
5. Step 5: Solve for x
   x = 1,425,770.88/1,381.68
6. Step 6: Final answer
   x = 1,031.91