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Finding the Fourth Proportional to 21.23, 31.65 and 20.99

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Solution

The fourth proportional to 21.23, 31.65 and 20.99 is: 31.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.23 : 31.65 = 20.99 : x
  2. Step 2: Convert to fraction form
    21.23/31.65 = 20.99/x
  3. Step 3: Cross multiply
    21.23x = 31.65 × 20.99
  4. Step 4: Simplify right side
    21.23x = 664.33
  5. Step 5: Solve for x
    x = 664.33/21.23
  6. Step 6: Final answer
    x = 31.29

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.