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Finding the Fourth Proportional to 1,321.22, 1,978.99 and 857.65

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Solution

The fourth proportional to 1,321.22, 1,978.99 and 857.65 is: 1,284.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,321.22 : 1,978.99 = 857.65 : x
  2. Step 2: Convert to fraction form
    1,321.22/1,978.99 = 857.65/x
  3. Step 3: Cross multiply
    1,321.22x = 1,978.99 × 857.65
  4. Step 4: Simplify right side
    1,321.22x = 1,697,270.88
  5. Step 5: Solve for x
    x = 1,697,270.88/1,321.22
  6. Step 6: Final answer
    x = 1,284.62

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