Question

[20 POINTS] At a certain high school, 15 students play stringed instruments, 20 students play brass instruments, and 5 students play neither stringed nor brass instruments. what is the probability that a randomly selected student plays either a string or brass instrument?

Answer 1

0.88

Explanation:

15/40+20/40=7/8

Converted into a decimal 0.875

then rounded to the nearest hundredth= 0.88

Answer 2

`P(A\cup B)= 0.875`

Explanation:

From the diagram, none of the students play both instruments.

This means the two events are mutually exclusive.

`P(A\cup B)=P(A)+P(B)`

The number of people playing instruments is 20.

`P(A\cup B)= (20)/(40) + (15)/(40)`

`P(A\cup B)= (35)/(40)`

`P(A\cup B)= 0.875`