In an honors math class of 25 students, 15 are boys and 10 are girls. On the final exam, 6 boys and 3 girls received a grade of A. If a student is chosen at random from this class, what is the probability of choosing a girl or a student who did not receive an A on the exam?
1
0.76
2
0.64
3
0.40
0.28
Submit Answer

Step-by-step explanation:

b=boy

a= a on the exam

b=15

b∩a=6

b'∩a=3

b'∪a'=?

b'∪a'= b'+a'-b'∩a'

a= b∩a+b'∩a (law of total probability) = 9

a'= 25-9 = 16

b'= 25-15= 10

16+10-7=19

19/25= .76

dude thats to long figure it

step-by-step explanation:

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1