91Ó°ÊÓ

The probability distribution is:

While listening to smoothing music, the expected number of puzzles in 5 minutes can be calculated as follows:

$\begin{array}{rcl}E\left(x\right)& =& ∑xp\left(x\right)\\ & =& 1(0.2)+2(0.4)+3(0.3)+4(0.1)\\ & =& 0.2+0.8+0.9+0.4\\ & =& 2.3\end{array}$

Thus, the likelihood that a randomly selected subject completes more problems than expected in a 5-minute period while listening to calming music can be computed as follows:

$\begin{array}{rcl}P(X& >& 2.3)=P(X=3)+P(X=4)\\ & =& 0.30+0.10\\ & =& 0.40\end{array}$

Therefore, the correct option is " b".

(a) The likelihood that a randomly selected participant completes more tasks than expected in a 5-minute period while listening to relaxing music will not be equal to $0.1.$

(c) The likelihood that a randomly selected participant completes more tasks than expected in a 5-minute period while listening to relaxing music will not be equal to $0.8$.

(d) The likelihood that a randomly selected participant completes more tasks than expected in a 5-minute period while listening to relaxing music will not be equal to $1$.

(e) The likelihood that a randomly selected participant completes more tasks than expected in a 5-minute period while listening to relaxing music Cannot be determined.