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Finding the Fourth Proportional to 857.87, 1,287.17 and 419.51

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Solution

The fourth proportional to 857.87, 1,287.17 and 419.51 is: 629.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.87 : 1,287.17 = 419.51 : x
  2. Step 2: Convert to fraction form
    857.87/1,287.17 = 419.51/x
  3. Step 3: Cross multiply
    857.87x = 1,287.17 × 419.51
  4. Step 4: Simplify right side
    857.87x = 539,983.38
  5. Step 5: Solve for x
    x = 539,983.38/857.87
  6. Step 6: Final answer
    x = 629.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.