Finding the Fourth Proportional to 100.77, 150.42 and 90.99

Step by Step Solution

1. Step 1: Write the proportion equation
   100.77 : 150.42 = 90.99 : x
2. Step 2: Convert to fraction form
   100.77/150.42 = 90.99/x
3. Step 3: Cross multiply
   100.77x = 150.42 × 90.99
4. Step 4: Simplify right side
   100.77x = 13,686.72
5. Step 5: Solve for x
   x = 13,686.72/100.77
6. Step 6: Final answer
   x = 135.82