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Finding the Fourth Proportional to 21.56, 31.91 and 21.51

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Solution

The fourth proportional to 21.56, 31.91 and 21.51 is: 31.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.56 : 31.91 = 21.51 : x
  2. Step 2: Convert to fraction form
    21.56/31.91 = 21.51/x
  3. Step 3: Cross multiply
    21.56x = 31.91 × 21.51
  4. Step 4: Simplify right side
    21.56x = 686.38
  5. Step 5: Solve for x
    x = 686.38/21.56
  6. Step 6: Final answer
    x = 31.84

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Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.