Self-study helps students to build confidence in learning. It boosts the self-esteem of the learners. Recent surveys suggested that close to 50% learners were self-taught using internet resources and upskilled themselves. A student may spend 1 hour to 6 hours in a day upskilling self. The probability distribution of the number of hours spent by a student is given below:
\[ P(X = x) = \begin{cases} kx^2 & {for } x = 1, 2, 3, \\ 2kx & {for } x = 4, 5, 6, \\ 0 & {otherwise}. \end{cases} \]
Based on the above information, answer the following:
Step 1: Apply the total probability rule. The sum of all probabilities must be 1: \[ k + 4k + 9k + 8k + 10k + 12k = 1. \]
Step 2: Determine the value of \( k \). Simplify the equation: \[ 44k = 1 \implies k = \frac{1}{44}. \]
Step 1: Apply the mean formula.
The mean (μ) is computed as the sum of each value (X) multiplied by its probability P(X): \[ \mu = \sum X \cdot P(X). \]
Step 2: Insert values from the distribution table.
Using the table data: \[ \mu = (1 \cdot k) + (2 \cdot 4k) + (3 \cdot 9k) + (4 \cdot 8k) + (5 \cdot 10k) + (6 \cdot 12k). \] Factor out k: \[ \mu = k(1 + 8 + 27 + 32 + 50 + 72). \]
Step 3: Simplify and determine μ.
\[ \mu = k \cdot 190. \] With \( k = \frac{1}{44} \), the mean is: \[ \mu = \frac{190}{44} = \frac{95}{22}. \]
Step 1: Determine the relevant range. We need the probability for \( X = 2, 3, 4, 5 \). This can be written as: \[ P(1 < X < 6) = P(X=2) + P(X=3) + P(X=4) + P(X=5) \]
Step 2: Substitute probabilities from the distribution table: \[ P(1 < X < 6) = 4k + 9k + 8k + 10k \]
Step 3: Simplify and calculate: \[ P(1 < X < 6) = 31k \] Substituting \( k = \frac{1}{44} \), \[ P(1 < X < 6) = \frac{31}{44} \]
Final Answer: \[ \boxed{\frac{31}{44}} \]
Self-study helps students to build confidence in learning. It boosts the self-esteem of the learners. Recent surveys suggested that close to 50% of learners were self-taught using internet resources and upskilled themselves.
A student may spend 1 hour to 6 hours in a day in upskilling self. The probability distribution of the number of hours spent by a student is given below:
\[ P(X = x) = \begin{cases} kx^2, & \text{for } x = 1, 2, 3, \\ 2kx, & \text{for } x = 4, 5, 6, \\ 0, & \text{otherwise.} \end{cases} \]
where \( x \) denotes the number of hours. Based on the above information, answer the following questions:
(i) Express the probability distribution given above in the form of a probability distribution table.
(ii) Find the value of \( k \).
(iii)(a) Find the mean number of hours spent by the student.
(iii)(b) Find \( P(1 < X < 6) \).
Questions number 19 and 20 are Assertion and Reason-based questions. Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C), and (D) as given below.
(A) Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.
When observed over a long period of time, a time series data can predict trends that can forecast increase, decrease, or stagnation of a variable under consideration. The table below shows the sale of an item in a district during 1996–2001:
\[ \begin{array}{|c|c|c|c|c|c|c|} \hline \textbf{Year} & 1996 & 1997 & 1998 & 1999 & 2000 & 2001 \\ \hline \textbf{Sales (in lakh ₹)} & 6.5 & 5.3 & 4.3 & 6.1 & 5.6 & 7.8 \\ \hline \end{array} \]