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Finding the Fourth Proportional to 55.45, 83.18 and 21.20

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Solution

The fourth proportional to 55.45, 83.18 and 21.20 is: 31.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    55.45 : 83.18 = 21.20 : x
  2. Step 2: Convert to fraction form
    55.45/83.18 = 21.20/x
  3. Step 3: Cross multiply
    55.45x = 83.18 × 21.20
  4. Step 4: Simplify right side
    55.45x = 1,763.31
  5. Step 5: Solve for x
    x = 1,763.31/55.45
  6. Step 6: Final answer
    x = 31.80

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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.