Finding the Fourth Proportional to 1,117.21, 1,538.86 and 780.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,117.21 : 1,538.86 = 780.52 : x
2. Step 2: Convert to fraction form
   1,117.21/1,538.86 = 780.52/x
3. Step 3: Cross multiply
   1,117.21x = 1,538.86 × 780.52
4. Step 4: Simplify right side
   1,117.21x = 1,201,111.01
5. Step 5: Solve for x
   x = 1,201,111.01/1,117.21
6. Step 6: Final answer
   x = 1,075.10