SOLUTION: A biologist estimates that 40% of the deer in a region carry a certain type of tick. For a sample of 300 deer selected at random, what is the chance that 124 or fewer deer have thi

Question 1085498: A biologist estimates that 40% of the deer in a region carry a certain type of tick. For a sample of 300 deer selected at random, what is the chance that 124 or fewer deer have this tick?

0.864

0.702

0.404

0.298

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
Expected value is 120
Can do it by 1 sample proportion (0.4133-0.4)/SE
std error is sqrt (p*(1-p))/300
=0.0283
(0.0133/0.0283)=z
z=0.47
probability z < 0.47 is 0.6808
B
Can use normal approximation
mean is 120
variance is 120*0.6 (np(1-p)=72
sd is sqrt (72)=8.484
(124-120)/8.484=0.4714=z
same answer.
In this instance want something close to 0.5 and greater than.
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