Finding the Fourth Proportional to 1,142.34, 1,575.78 and 721.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.34 : 1,575.78 = 721.86 : x
2. Step 2: Convert to fraction form
   1,142.34/1,575.78 = 721.86/x
3. Step 3: Cross multiply
   1,142.34x = 1,575.78 × 721.86
4. Step 4: Simplify right side
   1,142.34x = 1,137,492.55
5. Step 5: Solve for x
   x = 1,137,492.55/1,142.34
6. Step 6: Final answer
   x = 995.76