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Finding the Fourth Proportional to 53.79, 80.72 and 21.30

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Solution

The fourth proportional to 53.79, 80.72 and 21.30 is: 31.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    53.79 : 80.72 = 21.30 : x
  2. Step 2: Convert to fraction form
    53.79/80.72 = 21.30/x
  3. Step 3: Cross multiply
    53.79x = 80.72 × 21.30
  4. Step 4: Simplify right side
    53.79x = 1,719.34
  5. Step 5: Solve for x
    x = 1,719.34/53.79
  6. Step 6: Final answer
    x = 31.96

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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.