Finding the Fourth Proportional to 131.69, 196.78 and 90.79

Step by Step Solution

1. Step 1: Write the proportion equation
   131.69 : 196.78 = 90.79 : x
2. Step 2: Convert to fraction form
   131.69/196.78 = 90.79/x
3. Step 3: Cross multiply
   131.69x = 196.78 × 90.79
4. Step 4: Simplify right side
   131.69x = 17,865.11
5. Step 5: Solve for x
   x = 17,865.11/131.69
6. Step 6: Final answer
   x = 135.66