Answer:
If our random variable of interest for this case is X="the number of teenagers between 12-17 with smartphone" we can model the variable with this distribution:

And the mean for this case would be:

And the standard deviation would be given by:

Step-by-step explanation:
If our random variable of interest for this case is X="the number of teenagers between 12-17 with smartphone" we can model the variable with this distribution:

And the mean for this case would be:

And the standard deviation would be given by:

No Nothing Further Can Be Done
Answer:
the answer is 6 since from 1 side to the other it makes 12 you just divide 12 by 2 since O is in the middle and only goes to half of the line
X1,y1 = (-4,-2), x2, y2 = (9-2,-4)
could you check if 9-2 is actually correct, just I never seen it before
3. i=129; j=112
4.k=90;l=116;m=64;n=86
5.o=13;p=78;q=91
6.a=120;b=60;c=140
Can't see #7
You did 8 I believe
9.v=39;w=59;x=121
10.y=59;z=93
11.a=42;b=48;c=132
12.a=60;b=50;c=80;d=100