Answer: 19.77%
Step-by-step explanation:
Given: Mean : [tex]\mu=74[/tex]
Standard deviation : [tex]\sigma = 7.1[/tex]
The formula to calculate z-score is given by :_
[tex]z=\dfrac{x-\mu}{\sigma}[/tex]
For x= 80, we have
[tex]z=\dfrac{80-74}{7.1}\approx0.85[/tex]
The P-value = [tex]P(z>0.85)=1-P(z<0.85)=1-0.8023374=0.1976626[/tex]
In percent , [tex]0.1976626\times100=19.76626\%\approx19.77\%[/tex]
Hence, the approximate percentage of the test scores during the past year exceeded 80 =19.77%