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Finding the Fourth Proportional to 857.64, 1,286.40 and 491.28

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Solution

The fourth proportional to 857.64, 1,286.40 and 491.28 is: 736.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.64 : 1,286.40 = 491.28 : x
  2. Step 2: Convert to fraction form
    857.64/1,286.40 = 491.28/x
  3. Step 3: Cross multiply
    857.64x = 1,286.40 × 491.28
  4. Step 4: Simplify right side
    857.64x = 631,982.59
  5. Step 5: Solve for x
    x = 631,982.59/857.64
  6. Step 6: Final answer
    x = 736.89

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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.