A box contains 4 red pens,5 black pens, and 3 blue pens. If Robert selects one pen, and then another pen without putting the first pen back in the box, what is the probability that both pens will be black?

(p black) = 5/12

(p black) = 4/11

Step-by-step explanation:

Add the pens together to find the total

4 + 5 + 3 = 12

Find the probability of drawing the first black pen.

(p black) = 5/12

The black pen is not replaced, so now there are 11 pens in the box, and there are only 4 black pens.

Find the probability of drawing the second black pen.

(p black) = 4/11

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m

answer: 1) twenty-seven times y

              2) twenty-seven multiplied by y