Practice China questions with answers and explanations.
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There are 5 favourable outcomes out of 9 equally likely outcomes, so P(red)=5/9.
The dot product is 1×2+4×1=6.
Rewrite the value using base 2: 4 = 2^2. Matching exponents gives x = 2.
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Use the circle-area formula A = πr². Substituting r = 6 gives A = π × 6² = 36π.
Percentage=(7/32)×100=21.88.
Subtract 7 from both sides and divide by 8: x = (31-7)/8 = 3.
By Vieta’s formula, the sum of the roots equals the coefficient 18.
aₙ=a₁+(n−1)d=6+(6−1)×2=16.
By Vieta’s formula, the sum of the roots equals the coefficient 15.
aₙ=a₁+(n−1)d=5+(5−1)×1=9.
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The sum is n(n+1)/2=45, so the mean is 45/9.
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There are 4 favourable outcomes out of 7 equally likely outcomes, so P(red)=4/7.
