1
AP EAPCET 2025 - 21st May Evening Shift
MCQ (Single Correct Answer)
+1
-0

If the points $A, B, C, D$ with positions vectors $\hat{\mathbf{i}}+\hat{\mathbf{j}}-\hat{\mathbf{k}}, \hat{\mathbf{i}}-\hat{\mathbf{j}}+2 \hat{\mathbf{k}}, \hat{\mathbf{i}}-2 \hat{\mathbf{j}}+\hat{\mathbf{k}}, 2 \hat{\mathbf{i}}+\hat{\mathbf{j}}+\hat{\mathbf{k}}$ respectively form a tetrahedron, then the angle between the faces $A B C$ and $A B D$ of the tetrahedron is

A

$\cos ^{-1}\left(\frac{-4}{\sqrt{29}}\right)$

B

$\cos ^{-1}\left(\frac{-4}{5}\right)$

C

$\cos ^{-1}\left(\frac{3}{5}\right)$

D

$\cos ^{-1}\left(\frac{\sqrt{29}}{\sqrt{33}}\right)$

2
AP EAPCET 2025 - 21st May Evening Shift
MCQ (Single Correct Answer)
+1
-0

$\mathbf{a}, \mathbf{b}, \mathbf{c}$ are unit vectors. If $\mathbf{a}, \mathbf{b}$ are perpendicular vectors, $(\mathbf{a}-\mathbf{c}) \cdot(\mathbf{b}+\mathbf{c})=0$ and $\mathbf{c}=l \mathbf{a}+m \mathbf{b}+n(\mathbf{a} \times \mathbf{b}) ;$ ( $l, m, n$ are scalars), then $n^2=$

A

$I^2+m^2$

B

$-21 m$

C

$2 l-2 m$

D

$l m+l+m$

3
AP EAPCET 2025 - 21st May Evening Shift
MCQ (Single Correct Answer)
+1
-0

If the variance of the first $n$ natural numbers is 10 and the variance of the first $m$ even natural numbers is 16 , then $n: m=$

A

$9: 5$

B

$7: 3$

C

$11: 7$

D

$5: 8$

4
AP EAPCET 2025 - 21st May Evening Shift
MCQ (Single Correct Answer)
+1
-0

Given $f(x)=x^2-5 x+4$. Out of first 20 natural numbers, if a number $x$ is chosen at random, then the probability that the chosen $x$ satisfies the inequality $f(x)>10$ is

A

$\frac{1}{2}$

B

$\frac{3}{4}$

C

$\frac{7}{10}$

D

$\frac{13}{20}$