Finding the Fourth Proportional to 83.71, 126.27 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   83.71 : 126.27 = 78.72 : x
2. Step 2: Convert to fraction form
   83.71/126.27 = 78.72/x
3. Step 3: Cross multiply
   83.71x = 126.27 × 78.72
4. Step 4: Simplify right side
   83.71x = 9,939.34
5. Step 5: Solve for x
   x = 9,939.34/83.71
6. Step 6: Final answer
   x = 118.74