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Finding the Fourth Proportional to 30, 41.34 and 20.78

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Solution

The fourth proportional to 30, 41.34 and 20.78 is: 28.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    30 : 41.34 = 20.78 : x
  2. Step 2: Convert to fraction form
    30/41.34 = 20.78/x
  3. Step 3: Cross multiply
    30x = 41.34 × 20.78
  4. Step 4: Simplify right side
    30x = 859.05
  5. Step 5: Solve for x
    x = 859.05/30
  6. Step 6: Final answer
    x = 28.63

Related Problems

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Double scale
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Similar ratio
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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.