Finding the Fourth Proportional to 91.71, 137.46 and 42.90

Step by Step Solution

1. Step 1: Write the proportion equation
   91.71 : 137.46 = 42.90 : x
2. Step 2: Convert to fraction form
   91.71/137.46 = 42.90/x
3. Step 3: Cross multiply
   91.71x = 137.46 × 42.90
4. Step 4: Simplify right side
   91.71x = 5,897.03
5. Step 5: Solve for x
   x = 5,897.03/91.71
6. Step 6: Final answer
   x = 64.30