Finding the Fourth Proportional to 91.98, 137.86 and 78.23

Step by Step Solution

1. Step 1: Write the proportion equation
   91.98 : 137.86 = 78.23 : x
2. Step 2: Convert to fraction form
   91.98/137.86 = 78.23/x
3. Step 3: Cross multiply
   91.98x = 137.86 × 78.23
4. Step 4: Simplify right side
   91.98x = 10,784.25
5. Step 5: Solve for x
   x = 10,784.25/91.98
6. Step 6: Final answer
   x = 117.24