Finding the Fourth Proportional to 1,645.90, 2,271.38 and 899.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,645.90 : 2,271.38 = 899.91 : x
2. Step 2: Convert to fraction form
   1,645.90/2,271.38 = 899.91/x
3. Step 3: Cross multiply
   1,645.90x = 2,271.38 × 899.91
4. Step 4: Simplify right side
   1,645.90x = 2,044,021.72
5. Step 5: Solve for x
   x = 2,044,021.72/1,645.90
6. Step 6: Final answer
   x = 1,241.89