Science:Math Exam Resources/Courses/MATH101 C/April 2024/Question 17 (d)/Hint 1

Break the problem down into smaller parts: first find $\mathbb {E} (X^{2})$, then find the variance of $X$, then the standard deviation, then the desired interval.

Recall that the variance can be found using the formula $\mathrm {Var} (X)=\mathbb {E} (X^{2})-(\mathbb {E} X)^{2}$, and the standard deviation is just the square root of the variance.