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Finding the Fourth Proportional to 857.91, 1,287.21 and 511.41

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Solution

The fourth proportional to 857.91, 1,287.21 and 511.41 is: 767.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.91 : 1,287.21 = 511.41 : x
  2. Step 2: Convert to fraction form
    857.91/1,287.21 = 511.41/x
  3. Step 3: Cross multiply
    857.91x = 1,287.21 × 511.41
  4. Step 4: Simplify right side
    857.91x = 658,292.07
  5. Step 5: Solve for x
    x = 658,292.07/857.91
  6. Step 6: Final answer
    x = 767.32

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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.