Finding the Fourth Proportional to 90.96, 135.81 and 78.10

Step by Step Solution

1. Step 1: Write the proportion equation
   90.96 : 135.81 = 78.10 : x
2. Step 2: Convert to fraction form
   90.96/135.81 = 78.10/x
3. Step 3: Cross multiply
   90.96x = 135.81 × 78.10
4. Step 4: Simplify right side
   90.96x = 10,606.76
5. Step 5: Solve for x
   x = 10,606.76/90.96
6. Step 6: Final answer
   x = 116.61