Finding the Fourth Proportional to 1,379.98, 1,904.64 and 790.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.98 : 1,904.64 = 790.91 : x
2. Step 2: Convert to fraction form
   1,379.98/1,904.64 = 790.91/x
3. Step 3: Cross multiply
   1,379.98x = 1,904.64 × 790.91
4. Step 4: Simplify right side
   1,379.98x = 1,506,398.82
5. Step 5: Solve for x
   x = 1,506,398.82/1,379.98
6. Step 6: Final answer
   x = 1,091.61