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Finding the Fourth Proportional to 21.76, 30 and 21.60

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Solution

The fourth proportional to 21.76, 30 and 21.60 is: 29.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.76 : 30 = 21.60 : x
  2. Step 2: Convert to fraction form
    21.76/30 = 21.60/x
  3. Step 3: Cross multiply
    21.76x = 30 × 21.60
  4. Step 4: Simplify right side
    21.76x = 648
  5. Step 5: Solve for x
    x = 648/21.76
  6. Step 6: Final answer
    x = 29.78

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1.5x scale

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.