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Finding the Fourth Proportional to 1,287.92, 1,777.30 and 728.55

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Solution

The fourth proportional to 1,287.92, 1,777.30 and 728.55 is: 1,005.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.92 : 1,777.30 = 728.55 : x
  2. Step 2: Convert to fraction form
    1,287.92/1,777.30 = 728.55/x
  3. Step 3: Cross multiply
    1,287.92x = 1,777.30 × 728.55
  4. Step 4: Simplify right side
    1,287.92x = 1,294,850.09
  5. Step 5: Solve for x
    x = 1,294,850.09/1,287.92
  6. Step 6: Final answer
    x = 1,005.38

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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.