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Finding the Fourth Proportional to 30, 41.40 and 20.76

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Solution

The fourth proportional to 30, 41.40 and 20.76 is: 28.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    30 : 41.40 = 20.76 : x
  2. Step 2: Convert to fraction form
    30/41.40 = 20.76/x
  3. Step 3: Cross multiply
    30x = 41.40 × 20.76
  4. Step 4: Simplify right side
    30x = 859.46
  5. Step 5: Solve for x
    x = 859.46/30
  6. Step 6: Final answer
    x = 28.65

Related Problems

Find fourth proportional to 15, 20.70 and 10.38
Half scale
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Double scale
Find fourth proportional to 31, 42.78 and 21.76
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.