Question

$A=\{2,3,4,5\}$
$B=\{4,5,6,7,8\}$
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. $0.15$
• B. $0.20$
• C. $0.25$
• D. $0.30$
• E. $0.33$

Answer 1

Answer: (B)

$0.20$

Two integers will be randomly selected from the sets above, one integer from set A and one integer from set B. As there will be four pairs giving sum 9(one integer each from both sets), the probability will be:

the probability that the sum of the two integers will equal 9

$p=$$\frac{{}^4{C}_1}{{}^4{C}_1{\ast }^5{C}_1}$=$\frac{4}{4\ast 5}=0.20$