.
I will answer part (iii) only.
The class consists of 12 male = 3 non-B + 9 other male
and 18 females = 5 non-B + 13 other females.
The probability of selecting either a male or a non-B student = = . ANSWER
Solved.
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The formulas and the presentation itself are SELF-EXPLANATORY, i.e. do not require additional explanations.
The presentation itself is extremely compact and clear, making any additional words unnecessary.
Please post me, WHAT DO you THINK about it. Is it clear to you ?
I hope that after reading this post, you will tackle such problems as 2 x 2 = 4.