Probability
Aptitude

 Back to Questions
Q.

Set A = {2,3,4,5}

Set B = {4,5,6,7,8}

Two integers will be randomly selected from the sets above, one integer from Set $A$ and one integer from Set $B$.

What is the probability that the sum of the two integers will equal 9?

 A.

0.20

 B.

0.25

 C.

0.30

 D.

0.33

 Hide Ans

Solution:
Option(A) is correct

There are four ways of selectiing an integer from Set A = {2,3,4,5} AND there are 5 ways of selecting an integer from Set B = {4,5,6,7,8}.

So sample space,

$n(S)=4\times 5=20$

Now, favourable cases: {2, 7}, {3,6}, {4, 5}, {5, 4} i.e. 4 cases.

$n(E)=4$

$\therefore \text{Probability}= \dfrac{\text{Favorable Cases}}{\text{Total Cases}}$

\(P(E)=\dfrac{n(E)}{n(S)}\)

\(=\dfrac{4}{20}\)

\(=\textbf{0.20}\)


(0) Comment(s)