Answer:
The cutoff score should be 75.8 marks
Step-by-step explanation:
The cut-off should be set as the value corresponding to an area 15% in the normal distribution diagram.
Using the standard distribution tables we have value of standard normal deviate (Z) corresponding to area of 15% = -1.04
Thus we have
[tex]-1.04=\frac{X-\bar{X}}{\sigma }\\\\X=-1.04\times 5.5+81\\X=75.8[/tex]