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Finding the Fourth Proportional to 21.39, 32.25 and 20.78

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Solution

The fourth proportional to 21.39, 32.25 and 20.78 is: 31.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.39 : 32.25 = 20.78 : x
  2. Step 2: Convert to fraction form
    21.39/32.25 = 20.78/x
  3. Step 3: Cross multiply
    21.39x = 32.25 × 20.78
  4. Step 4: Simplify right side
    21.39x = 670.16
  5. Step 5: Solve for x
    x = 670.16/21.39
  6. Step 6: Final answer
    x = 31.33

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.