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Finding the Fourth Proportional to 1,287.68, 1,776.96 and 939.84

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Solution

The fourth proportional to 1,287.68, 1,776.96 and 939.84 is: 1,296.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.68 : 1,776.96 = 939.84 : x
  2. Step 2: Convert to fraction form
    1,287.68/1,776.96 = 939.84/x
  3. Step 3: Cross multiply
    1,287.68x = 1,776.96 × 939.84
  4. Step 4: Simplify right side
    1,287.68x = 1,670,058.09
  5. Step 5: Solve for x
    x = 1,670,058.09/1,287.68
  6. Step 6: Final answer
    x = 1,296.95

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.