Finding the Fourth Proportional to 101.15, 151.42 and 90.72

Step by Step Solution

1. Step 1: Write the proportion equation
   101.15 : 151.42 = 90.72 : x
2. Step 2: Convert to fraction form
   101.15/151.42 = 90.72/x
3. Step 3: Cross multiply
   101.15x = 151.42 × 90.72
4. Step 4: Simplify right side
   101.15x = 13,736.82
5. Step 5: Solve for x
   x = 13,736.82/101.15
6. Step 6: Final answer
   x = 135.81