This is a permutation question as the ordering is important. All the three ways mentioned are important in this question.
The practice problem's solution:
A] 9/32 as the order is not confirm, we shall have 3 possibilities as follows:
1. {H, H, H, T, T}
2. {T, T, H, H, H}
3. {T, H, H, H, T}
4. {T, H, T, H, H}
5. {T, H, H, T, H}
6. {H, T, H, H, T}
7. {H, T, T, H, H}
8. {H, H, T, T, H}
9. {H, T, H, T, H}
B] The answer is 3/16 . The probability of getting 4 heads at least is as follows:
1. {H, H, H, H, T}
2. {H, H, H, T, H}
3. {H, H, T, H, H}
4. {H, T, H, H, H}
5. {T, H, H, H, H}
6. {H, H, H, H, H}
In all 6 ways and all of them having a probability of 1/2 hence 6/32 = 3/16.
I really hope I am correct. As per the formula this is what it should be...
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