91Ó°ÊÓ

The gypsy moth is a serious threat to oak and aspen trees. A state agriculture department places traps throughout the state to detect the moths. When traps are checked periodically, the mean number of moths trapped is only $0.5$, but some traps have several moths. The distribution of moth counts is discrete and strongly skewed, with standard deviation $0.7$.

Population mean$\left(\mathrm{μ}\right)=0.50$

Population standard deviation$\left(\mathrm{σ}\right)=0.7$

Sample size $\left(n\right)=50$

The mean and standard deviation can be calculated as:

${\mathrm{μ}}_{\stackrel{¯}{x}}=\mathrm{μ}=0.5$

$$\begin{gathered} {\mathrm{σ}}_{\stackrel{¯}{x}}=\frac{\mathrm{σ}}{\sqrt{n}} \\ =\frac{0.7}{\sqrt{50}} \\ =0.0990 \end{gathered}$$

The required mean and standard deviation are $0.5$and $0.0990$respectively

The gypsy moth is a serious threat to oak and aspen trees. A state agriculture department places traps throughout the state to detect the moths. When traps are checked periodically, the mean number of moths trapped is only $0.5$, but some traps have several moths. The distribution of moth counts is discrete and strongly skewed, with standard deviation$0.7.$

The probability that average number of months is greater than $0.6$can be calculated as:

$$\begin{gathered} P(\stackrel{¯}{x}â‰\yen 0.6)=P\left(Zâ‰\yen \frac{0.6-0.5}{\frac{0.7}{\sqrt{30}}}\right) \\ =P(Zâ‰\yen 1.01) \\ =0.1562 \end{gathered}$$

Thus, the probability is $0.1562$.