Answer:
The answer is "[tex]10 \% ,\text{upper limit}=52,\ and \ \text{lower limit}=28[/tex]"
Step-by-step explanation:
Given value:
[tex]\mu =40\\\\\sigma=4[/tex]
In point a:
Calculating the value of the coefficient of variation:
[tex]\to C.V= \frac{6}{\mu} \times 100 \%\\\\ \to C.V= \frac{4}{\mu} \times 100 \% \\\\ \to C.V = 10 \%[/tex]
In point B:
when 88.9 \% of the value are lies then :
[tex]\to \mu \pm 36\\\\\to \mu -36 = 40-3\times 4 = 40 -12 =28\\\\\to \mu +36 = 40+3\times 4 = 40 +12 =52[/tex]
[tex]\text{upper limit}=52\\\\\text{lower limit}=28[/tex]