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Finding the Fourth Proportional to 1,288.36, 1,778 and 728.86

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Solution

The fourth proportional to 1,288.36, 1,778 and 728.86 is: 1,005.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.36 : 1,778 = 728.86 : x
  2. Step 2: Convert to fraction form
    1,288.36/1,778 = 728.86/x
  3. Step 3: Cross multiply
    1,288.36x = 1,778 × 728.86
  4. Step 4: Simplify right side
    1,288.36x = 1,295,913.08
  5. Step 5: Solve for x
    x = 1,295,913.08/1,288.36
  6. Step 6: Final answer
    x = 1,005.86

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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.