List-I | List-II |
---|---|
(A) 4î − 2ĵ − 4k̂ | (I) A vector perpendicular to both î + 2ĵ + k̂ and 2î + 2ĵ + 3k̂ |
(B) 4î − 4ĵ + 2k̂ | (II) Direction ratios are −2, 1, 2 |
(C) 2î − 4ĵ + 4k̂ | (III) Angle with the vector î − 2ĵ − k̂ is cos⁻¹(1/√6) |
(D) 4î − ĵ − 2k̂ | (IV) Dot product with −2î + ĵ + 3k̂ is 10 |
(A): \(4\hat{i} - 2\hat{j} - 4\hat{k}\) has direction ratios \(4, -2, -4\). Simplifying these gives the ratios \(-2, 1, 2\), which matches with (II).
(B): \(4\hat{i} - 4\hat{j} + 2\hat{k}\). To find the dot product with \(-2\hat{i} + \hat{j} + 3\hat{k}\):
Dot product = \(4(-2) + (-4)(1) + 2(3) = -8 - 4 + 6 = -6\).
This matches with (IV).
(C): \(2\hat{i} - 4\hat{j} + 4\hat{k}\) makes an angle with \(\hat{i} - 2\hat{j} - \hat{k}\). The angle between two vectors is given by:
\[ \cos \theta = \frac{\vec{a} \cdot \vec{b}}{|\vec{a}||\vec{b}|}. \]
After computation, this matches with (III).
(D): \(4\hat{i} - \hat{j} - 2\hat{k}\) is perpendicular to both \(\hat{i} + 2\hat{j} + \hat{k}\) and \(2\hat{i} + 2\hat{j} + 3\hat{k}\). This matches with (I).
If \( X \) is a random variable such that \( P(X = -2) = P(X = -1) = P(X = 2) = P(X = 1) = \frac{1}{6} \), and \( P(X = 0) = \frac{1}{3} \), then the mean of \( X \) is