Question

Solve all questions by using SPSS. Question No 1: It is conjectured that an impurity exists in 30% of all drinking wells in a certain rural community. In order to gain some insight into the true extent of the problem, it is determined that some testing is necessary. It is too expensive to test all of the wells in the area, so 10 are randomly selected for testing. Find the probability in each case: (a) What is the probability that at least 3 wells have the impurity? (b) More than 2 but less than 5 wells have the impurity. Answer Mathematical Notation SPSS Code Part (a) Part (b) Write steps:

Answer 1

From the given information, we find:

n= 10

p= 0.30

We want,

a) P(X>=3) = 1- P(X<=2)

SPSS code: CDF.BINOM(2, 10, 0.3)

Through this we would find, P(X<=2) = 0.3828

So required answer is: 1-0.3828 = 0.6172

b) P(2<X<5) = P(X<=4) - P(X<=2) (Since we want x=3,4 here)

SPSS code: CDF.BINOM(4,10,0.3) - CDF.BINOM(2,10,0.3)

The required answer is: 0.4669