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Finding the Fourth Proportional to 53.20, 79.78 and 21.16

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Solution

The fourth proportional to 53.20, 79.78 and 21.16 is: 31.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    53.20 : 79.78 = 21.16 : x
  2. Step 2: Convert to fraction form
    53.20/79.78 = 21.16/x
  3. Step 3: Cross multiply
    53.20x = 79.78 × 21.16
  4. Step 4: Simplify right side
    53.20x = 1,688.14
  5. Step 5: Solve for x
    x = 1,688.14/53.20
  6. Step 6: Final answer
    x = 31.73

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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.