Finding the Fourth Proportional to 78.23, 117.34 and 61.15

Step by Step Solution

1. Step 1: Write the proportion equation
   78.23 : 117.34 = 61.15 : x
2. Step 2: Convert to fraction form
   78.23/117.34 = 61.15/x
3. Step 3: Cross multiply
   78.23x = 117.34 × 61.15
4. Step 4: Simplify right side
   78.23x = 7,175.34
5. Step 5: Solve for x
   x = 7,175.34/78.23
6. Step 6: Final answer
   x = 91.72