Twenty students compete in a school-wide marathon and each student is of comparable running ability. Of the 20 students, 15 were boys and 5 were girls. What is the probability that boys will place 1st, 2nd, and 3rd in the marathon?

0.3991

Step-by-step explanation:

Number of Boys=15

Number of Girls =5

Total=15+5=20

Note that as each boy wins, the number of male contestants reduces. Thus is a probability of selecting an item without replacement.

P(1st boy winning) = 15/20

P(2nd boy winning) =14/19

P(3rd boy winning)=13/18

Therefore:

P(boys will place 1st, 2nd, and 3rd in the marathon)

= 15 /20 X 14/19 X 13/18

=91/228

=0.3991

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,

y=3x+4

step-by-step explanation:

given the points a(0,4) and b(-4, -8)

eqn of line ab: (y-4)/(x-0)=(-8-4)/(-4-0)

(y-4)/x=-12/-4=3

y=3x+4