Math: Counting Principles and Probability CONFUSION MY GOODNES

dougiezmd
Thu, 02 Jan 2014 02:24:58 +0000

im getting suicidal and depression about math im so sad

so sad

idk wat happend i used to get really good scores on my math like 800 and 770 but now i get crap that has not broken 750 in a long time. im aiming for 800 on this january SAT

IM SO CONFUSED, I THOUGHT I HAD IT UNDER MY BELT BUT I DONT:

So, the question was “Parallelogram with no right angles, what is the probability that two randomly chosen angles are supplementary”

my thought process

o well, 4 angles can be chosen as the first one leaving me with 3 angles left to be chosen for the second one; therefore, there are 12 combinations total, right? err…

so after that, I listed out all the angle combos that add to 180-> 4 combos
4/12-> 1/3

the answer was 2/3, i was confused so i wrote all the possibilities in a table and only came up with 6 combinations…

so what does 4*3 represent? all the combinations and their variations? (ie: AB and BA are counted separately)

im seriously confused… why didn’t my way work?

also i was infuriated even further when i got a second question wrong earlier on the same set because i said 4/24I3/24 but it should have been 4/243/23. i really did not see that and i admit it was not a stupid mistake, it was a mistake i should be really scared about…

im really anxious now… can anybody post a link to some counting and probability excercises?