Knees Patients receiving artificial knees often experience pain after surgery. The pain is measured on a subjective scale with possible values of 1 (low) to 5 (high). Let X be the pain score for a randomly selected patient. The following table gives part of the probability distribution for X.
Value $1$ $2$ $3$ $4$ $5$
Probability $0.1$ $0.2$ $0.3$ $0.3$ ?
(a) Find $P (X = 5)$
(b) If two patients who received artificial knees are chosen at random, what’s the probability that both of them report pain scores of $1$ or $2$ ? Show your work.
(c) Compute the mean and standard deviation of $X$ . Show your work.

Question

Accepted Answer

(a) $P (X = 5) = 0.1$

(b) $P (1 or 2) = 0.09$

(c) Mean= $3.1$

Standard deviation= $1.14$

Short Answer

Value	$1$	$2$	$3$	$4$	$5$
Probability	localid="1649746499147" $0.1$	localid="1649746505085" $0.2$	localid="1649746511170" $0.3$	localid="1649746516856" $0.3$	??