Finding the Fourth Proportional to 2,645.21, 3,967.20 and 890.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,645.21 : 3,967.20 = 890.30 : x
2. Step 2: Convert to fraction form
   2,645.21/3,967.20 = 890.30/x
3. Step 3: Cross multiply
   2,645.21x = 3,967.20 × 890.30
4. Step 4: Simplify right side
   2,645.21x = 3,531,978.32
5. Step 5: Solve for x
   x = 3,531,978.32/2,645.21
6. Step 6: Final answer
   x = 1,335.24