Question

This year, 75% of the graduating class of Harriet Tubman High School had taken at least 8 math courses. Of the remaining class members, 60% had taken 6 or 7 math courses. What percent of the graduating class had taken fewer than 6 math courses? A. 0% B. 10% C. 15% D. 30% E. 45%

Answer 1

`P(E) = 0.25*0.4=0.1`

B. 10%

Explanation:

Let X denote the random variable "Number of courses taking by one student in the Harriet Tubman High School"

For this case we have that information given:

75% of the graduating class of Harriet Tubman High School had taken at least 8 math courses

And that means 25% of the total are taking 7 or less courses

`P(X =6 U X=7) =0.60`

And by the complement rule we can find
`P(X<6) =1-0.6=0.4`

And then we can find the probability required like this:

Let E the event:

E=" A student had taken fewer than 6 math courses"

`P(E) = 0.25*0.4=0.1`

B. 10%