Finding the Fourth Proportional to 99.63, 137.50 and 76.21

Step by Step Solution

1. Step 1: Write the proportion equation
   99.63 : 137.50 = 76.21 : x
2. Step 2: Convert to fraction form
   99.63/137.50 = 76.21/x
3. Step 3: Cross multiply
   99.63x = 137.50 × 76.21
4. Step 4: Simplify right side
   99.63x = 10,478.34
5. Step 5: Solve for x
   x = 10,478.34/99.63
6. Step 6: Final answer
   x = 105.17