Answer:
a) Mean shoe size = 7.8
b) 8.8, 9.8 and 10.8
c) see attached
d) Shoe size
Step-by-step explanation:
[tex]\sf Mean \ \mu= 7.8[/tex]
[tex]\sf Standard \ deviation \ \sigma= 1[/tex]
Therefore,
[tex]\sf 1 \sigma=\mu+1 \sigma=7.8+1=8.8\\\sf 2 \sigma=\mu+2 \sigma=7.8+2 \cdot 1=9.8\\\sf 3 \sigma=\mu+3 \sigma=7.8+3 \cdot 1=10.8[/tex]
