75 points all freshmen, sophomores, juniors, and seniors attended a high school assembly. the total student attendance is shown in the table. twice during the assembly, a student is chosen at random to assist with the presentation. after the first student has finished assisting, the student returns to the group and can be chosen a second time. what is the probability that the first student chosen is a senior and the second student chosen is a sophomore?
a. 11/320
b. 3/80
c. 11/40
d. 2/5

- A is the right answer .

Probability that the first student chosen is a senior and the second student chosen is a sophomore=

Explanation:-

According to the given table,

Total students=31+10+17+22= 80

Number of senior students = 22

Let A be the event 1 of choosing first student a senior

Then Probability of choosing first student a senior P(A) =

Now, Number of sophomores = 10

Let B be the event 2 of choosing second student a sophomore after replacing first student.

Then Probability of choosing second student a sophomore P(B)=

As it is an independent event, then probability that the first student chosen is a senior and the second student chosen is a sophomore=P(A)×P(B)=