n(U) = 20
n(G) = 12
n(P) = 7
[tex]\text{ n(G u P)}^1=4[/tex]Let x represent students that play both instruments
n(PuG) = x
A. Venn diagram
B. What is the probability that a randomly selected student will play guitar and piano?
Firstly solve for x
12-x + x + 7-x + 4 = 20
23-x = 20
-x = 20 - 23
-x = -3
x = 3
Number of students that play guitar and piano = x = 3
Total students = 20
Probability that a randomly selected student will play guitar and piano = 3/20
C. What is the probability that a randomly selected student will play one of these two instruments?
[tex]\begin{gathered} \text{ = }\frac{12-x}{20}\text{ +}\frac{7-x}{20} \\ =\frac{12-3}{20}+\frac{7-3}{20} \\ =\frac{9}{20}+\frac{4}{20} \\ =\frac{13}{20} \end{gathered}[/tex]D. What is the probability that a randomly selected student will not play the piano?
Students who do not play piano are students that play guitar only and students who do not play any instrument
students that play guitar only = 12 -x = 12 -3 = 9 students
students who do not play any instrument = 4
Probability that a randomly selected student will not play the piano =
[tex]\frac{9}{20}+\frac{4}{20}\text{ = }\frac{13}{20}[/tex]
