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Finding the Fourth Proportional to 112.80, 169.20 and 67.20

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Solution

The fourth proportional to 112.80, 169.20 and 67.20 is: 100.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.80 : 169.20 = 67.20 : x
  2. Step 2: Convert to fraction form
    112.80/169.20 = 67.20/x
  3. Step 3: Cross multiply
    112.80x = 169.20 × 67.20
  4. Step 4: Simplify right side
    112.80x = 11,370.24
  5. Step 5: Solve for x
    x = 11,370.24/112.80
  6. Step 6: Final answer
    x = 100.80

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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.