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Finding the Fourth Proportional to 31, 42.72 and 22.80

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Solution

The fourth proportional to 31, 42.72 and 22.80 is: 31.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    31 : 42.72 = 22.80 : x
  2. Step 2: Convert to fraction form
    31/42.72 = 22.80/x
  3. Step 3: Cross multiply
    31x = 42.72 × 22.80
  4. Step 4: Simplify right side
    31x = 974.02
  5. Step 5: Solve for x
    x = 974.02/31
  6. Step 6: Final answer
    x = 31.42

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.