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Finding the Fourth Proportional to 42.80, 64.19 and 12.36

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Solution

The fourth proportional to 42.80, 64.19 and 12.36 is: 18.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.80 : 64.19 = 12.36 : x
  2. Step 2: Convert to fraction form
    42.80/64.19 = 12.36/x
  3. Step 3: Cross multiply
    42.80x = 64.19 × 12.36
  4. Step 4: Simplify right side
    42.80x = 793.49
  5. Step 5: Solve for x
    x = 793.49/42.80
  6. Step 6: Final answer
    x = 18.54

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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.