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Finding the Fourth Proportional to 386.72, 580 and 112.80

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Solution

The fourth proportional to 386.72, 580 and 112.80 is: 169.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.72 : 580 = 112.80 : x
  2. Step 2: Convert to fraction form
    386.72/580 = 112.80/x
  3. Step 3: Cross multiply
    386.72x = 580 × 112.80
  4. Step 4: Simplify right side
    386.72x = 65,424
  5. Step 5: Solve for x
    x = 65,424/386.72
  6. Step 6: Final answer
    x = 169.18

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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.