Finding the Fourth Proportional to 91.90, 126.71 and 78.94

Step by Step Solution

1. Step 1: Write the proportion equation
   91.90 : 126.71 = 78.94 : x
2. Step 2: Convert to fraction form
   91.90/126.71 = 78.94/x
3. Step 3: Cross multiply
   91.90x = 126.71 × 78.94
4. Step 4: Simplify right side
   91.90x = 10,002.49
5. Step 5: Solve for x
   x = 10,002.49/91.90
6. Step 6: Final answer
   x = 108.84