Question

Find p(2)

Find p(2 or fewer)

Answer 1

P(2)=0.021942 approximately

P(2 or fewer)=0.02711 approximately

Explanation:

`P(x)=(n choose x) *p^x * q^(n-x)`

x is the number of successes desired

p is probability of getting a success per trial

n is the number of trials

q is 1-p

So n=15 and p=.4 here

And you want to know P(2) which means x is 2

Plug in this information

`P(2)=(15 \text{ choose } 2) *.4^2 * .6^(15-2)`

Just plug into calculator... P(2)=0.021942 approximately

For p(2 or fewer) you just do P(0)+P(1)+P(2)

I already found P(2)

You need to find P(1)

Once you get P(1), add that result to 0.021942.

Try to do part b and I will tell you if you got it right or not.

So P(2 or less) is P(0)+P(1)+P(2)

So to complete this we need to find P(1) and almost forgot P(0)...

We already have P(2).

P(0)=(15 choose 0) *.4^0*.6^(15-0)=0.00047

P(1)=(15 choose 1) *.4^1 *.6^(15-1)=.004702

Now P(2)=0.021942

--------------------------add these

0.027114 approximately