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Finding the Fourth Proportional to 857.97, 1,287.88 and 642.92

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Solution

The fourth proportional to 857.97, 1,287.88 and 642.92 is: 965.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.97 : 1,287.88 = 642.92 : x
  2. Step 2: Convert to fraction form
    857.97/1,287.88 = 642.92/x
  3. Step 3: Cross multiply
    857.97x = 1,287.88 × 642.92
  4. Step 4: Simplify right side
    857.97x = 827,995.76
  5. Step 5: Solve for x
    x = 827,995.76/857.97
  6. Step 6: Final answer
    x = 965.06

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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.