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Finding the Fourth Proportional to 485.36, 728.16 and 138.69

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Solution

The fourth proportional to 485.36, 728.16 and 138.69 is: 208.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.36 : 728.16 = 138.69 : x
  2. Step 2: Convert to fraction form
    485.36/728.16 = 138.69/x
  3. Step 3: Cross multiply
    485.36x = 728.16 × 138.69
  4. Step 4: Simplify right side
    485.36x = 100,987.82
  5. Step 5: Solve for x
    x = 100,987.82/485.36
  6. Step 6: Final answer
    x = 208.07

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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.