Finding the Fourth Proportional to 90.51, 124.79 and 72.15

Step by Step Solution

1. Step 1: Write the proportion equation
   90.51 : 124.79 = 72.15 : x
2. Step 2: Convert to fraction form
   90.51/124.79 = 72.15/x
3. Step 3: Cross multiply
   90.51x = 124.79 × 72.15
4. Step 4: Simplify right side
   90.51x = 9,003.24
5. Step 5: Solve for x
   x = 9,003.24/90.51
6. Step 6: Final answer
   x = 99.47