1 red marble 4 blue marbles 3 green marbles probability of drawing 2 blue marbles

4/10

Step-by-step explanation:

3/14

Step-by-step explanation:

Assuming you draw one after the other without replacement, you have a 1/2 chance of drawing blue the first time, and after one is taken out, you have 7 left. In order to draw 2 blues you would have to have a blue the first time, so there would be 3 blue left. Multiplying the 2 probabilities gets 1/2*3/7= 3/14. Double check that though.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.