Finding the Fourth Proportional to 1,071.16, 1,478.44 and 678.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,071.16 : 1,478.44 = 678.72 : x
2. Step 2: Convert to fraction form
   1,071.16/1,478.44 = 678.72/x
3. Step 3: Cross multiply
   1,071.16x = 1,478.44 × 678.72
4. Step 4: Simplify right side
   1,071.16x = 1,003,446.80
5. Step 5: Solve for x
   x = 1,003,446.80/1,071.16
6. Step 6: Final answer
   x = 936.79