MCQ
The solution set of the inequation $|\text{x}+2|\leq5$ is:
- A(-7, 5)
- B[-7, 3]
- C[-5, 5]
- D(-7, 3)
Solution:
$|\text{x}+2|\leq5$
$\Rightarrow-5\leq\text{x}+2\leq5$
$\Rightarrow-5-2\leq\text{x}+2-2\leq5-2$
$\Rightarrow-7\leq\text{x}\leq3$
$\Rightarrow\text{x}\in[-7,3]$
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The real value of $\theta$ for which the expression $\frac{1+\text{i}\cos\theta}{1-2\text{i}\cos\theta}$ is a real number is:
$\text{n}\pi+\frac{\pi}{4}$
$\text{n}\pi+(-1)^{\text{n}}\frac{\pi}{4}$
$2\text{n}\pi\pm\frac{\pi}{2}$
None of these.
The following information relates to a sample of size 60 $\sum\text{x}^2=18000$ and $\sum\text{x}=960,$ then the variance is: