SOLUTION: In Canada, 72% of the voters are not in favour of the reinstatement of the death penalty. If three voters were selected at random what is the probability that: 1. exactly 2 were

Question 1167767: In Canada, 72% of the voters are not in favour of the reinstatement of the death penalty. If three voters were selected at random what is the probability that:
1. exactly 2 were not in favour of the death penalty. got this as 0.435
2. at most 2 were not in favour of the death penalty got this as 0.627
3. at least 2 were not in favour of the death penalty got this as 0.809
If n = 10 voters are observed.
1. Find the probability at least 7 do not favour the death penalty
2. Find the probability at least 6 and at most 8 do not favour the death
3. Find the probability at most 5 do not favour the death penalty penalty.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The first two are correct.
At least 2 were not in favor should be low probability.
That is 2 not in favor (1 in favor) which has probability 0.1693, and 3 not in favor, which is .28^3 or 0.0220
That sum is 0.1913, which is the complement of your answer,
for 10, at least 7 means 7,8,9,10 is 0.7021 from the calculator
for 7 it is 10C7=120*.72^7*.28^3=0.2642
for 8 it is 45*0.72^8*0.28^2=0.2548
for 9 it is 10*0.72^9*0.28=0.1456
for 10 it is .72^10=0.0373
That sum is 0.7019. The 0.7021 is without rounding, so use that.
at least 6 an at most 8 is 6,7,8. We have the latter two already
binomialpdf for 6 is 0.1798.
the answer is 0.6988.
at most 5 is probability 0.1181 from the calculator binomcdf(10,72,5) ENTER.
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