Finding the Fourth Proportional to 90.42, 135.42 and 59.91

Step by Step Solution

1. Step 1: Write the proportion equation
   90.42 : 135.42 = 59.91 : x
2. Step 2: Convert to fraction form
   90.42/135.42 = 59.91/x
3. Step 3: Cross multiply
   90.42x = 135.42 × 59.91
4. Step 4: Simplify right side
   90.42x = 8,113.01
5. Step 5: Solve for x
   x = 8,113.01/90.42
6. Step 6: Final answer
   x = 89.73